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      01-12-2011, 06:29 PM   #1
Arxangel
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Need advice on Z4 3.0si exhaust system, cat, and air filter!!!

Hello guys, I am new to this forum, and although not new to BMW, the Z4 3.0 si is the first BMW that I actually own and will have the pleasure of tuning.

Since I am very concerned with engine longevity I try to avoid getting a chip without upgrading the cooling system. Sadly, I could not find a kit for the E86 Z4 3.0 si that contains a chip and a cooling system upgrade, so for now I will only concentrate on the easier bits.

So here goes my question. What exhaust system, sport/racing cat and sport/racing air filter can anyone recommend that would give a combined boost in power of at least 25-30bhp?

Thanks in advance to all who help

Last edited by Arxangel; 01-14-2011 at 04:18 AM.
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      01-13-2011, 04:18 AM   #2
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Because you are in Europe I'm assuming you have the Euro version with catless headers. In this case, replacing section 1 of the exhaust with a catless system will yield the most gains, but make your Z4 illegal at the same time. Other than that, check out reflashes from AA, Bren Tuning, ESS, etc. Typically the limit on these engines isn't the heat they produce, so I wouldn't worry about an uprated cooling system.

You might get a combined 15 hp out of a tune and section 1 cat delete.
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      01-13-2011, 06:15 AM   #3
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Thank you for the reply pokeybritches, however, removing the cat is not an option. Even though a lot of people in Bulgaria do that, I would prefer not to mess with it but rather to replace it with a racing one (if at all possible).

As for the chip, I already said that I am not a fan of doing it, unless I uprate the cooling system even if it only involves getting a more powerful fan.

Can you recommend and air filter and/or an exhaust system that would be available here in Europe that would give me the desired 25-30 bhp gain?
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      01-14-2011, 04:22 AM   #4
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Come on guys, seriously, I need some help with that. I do understand that most of you drive a Z4 M version of the car, or at least this is the impression I get from reading around the forum, but I really hope that there will be one or two 3.0si owners that would be able to help me out.

Just to make a quick clarification, when I say I want to replace the exhaust I mean from headers to mufflers, out with the old in with the new, 100% new system from start to finish. And I am also willing to spend a good amount on it.

Another question, I read around the forum about the PRi Intake Scoop, and am thinking of ordering one, but can anyone suggest a sport air filter to use along with the scoop since the one that comes in the KIT is for the M version only?
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      01-14-2011, 07:28 AM   #5
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I'm really not of much help with the n52 engine in the 3.0si, but if u're looking at a complete aftermarket exhaust setup, i know a catless section 1 will produce the most gains, since the heirarchy of performance gains from modifying ur exhaust starts up at the headers. u could get redesigned headers for better flow, race cats in section 1, a modified x-pipe and ur choice of mufflers (capristo has a set for the 3.0si tt sounds amazing). i really don't know if all this is going to be able to yield 25-30bhp, again, i'm not familiar with the n52.

i believe txz4 got himself a new drop-in filter for his 3.0si coupe and also put on a stebro muffler. u could pm him for additional info.
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      01-14-2011, 08:11 AM   #6
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Well the idea is not to remove the cat but rather to use a race one. Also I am looking to gain 25-30bhp not from the exhaust alone but also from changing the air filter and adding the RPi Intake Scoop.

I am also open to suggestions about a 2x dual exhaust system, meaning to make it look like the M version with left and right exhausts. I am willing to swap for the M bumper if needed.
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      01-14-2011, 08:26 AM   #7
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rpi scoop and drop-in filter will net u 5bhp at the most, and that will more than likely only be at speed. perhaps u can consider swapping ur differential? consistent gains through both power and torque bands at the expense of fuel economy.
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      01-14-2011, 09:00 AM   #8
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rpi scoop and drop-in filter will net u 5bhp at the most, and that will more than likely only be at speed. perhaps u can consider swapping ur differential? consistent gains through both power and torque bands at the expense of fuel economy.
haha Well in terms of fuel economy, my company car is diesel and I have to say that my heart still hurts when I see the average consumption on the Z4, especially when I am in the "mood" . Basically I would not want it to go any higher.

As for the RPi scoop, I have read around the forum and tests have shown that actually the scoop alone gives 5rwhp in NOT perfect conditions, which means that the bhp should go a bit higher up. Also having the power increase at speed is not a bad thing. Actually, when I think about it, this is exactly where I want the boost to be, after all you don't race at 40mph, you race at over 70mph
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      01-14-2011, 09:06 AM   #9
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(capristo has a set for the 3.0si tt sounds amazing)
Actually I just checked out Capristo's website, and I did not find anything for any BMW.
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      01-14-2011, 09:39 AM   #10
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Actually I just checked out Capristo's website, and I did not find anything for any BMW.
They made a custom system for at least one 3.0si. It must've costed a fortune though! The V6 Audi TT system is 3.500 euro! It does sound gorgeous though.

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      01-14-2011, 09:41 AM   #11
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With a sound like that I am surprised that they have not yet pushed a Z4 system to production. I am sure there will be no lack of customers.
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      01-14-2011, 09:45 AM   #12
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You might also want to check this out: http://www.supersprint.com/USP0000bmwZ46.asp
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      01-14-2011, 10:22 AM   #13
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The only exhaust that I know of that fits the 3.0si is Bastuck. Supersprint offers one but last time I checked, it was really meant for the 03-05 models, and thus does not fit well on the 06-08 models (it will hang too low). Arqray also offers one specific to the 3.0si but it is only a muffler.

The only software upgrade I am aware of is Active Autworks and Gintani although if it were me, I would go with AA (seems like based on recent reviews, AA has smoother power delivery although Gintani might offer more peak hp). Expect around 8hp increase for both tunes.

Filters, not really much out there besides Afe but they get mixed reviews, (check e90post under the NA tuning section). I'd stick with the oem box and just replace the paper filter with something else. I used to have great experience with ITG Air filters but I think they only have something for the m54 engine. I asked about 06-08 Z4s and they redirected me to the 03-05, saying it would fit but I was skeptical.

Exhausts for 03-05:
Supersprint (everything available, from headers down to muffler)
Milltek (midpipe & muffler)
Bastuck (midpipe & muffler)
Eisenmann (midpipe & muffler)
Dinan (muffler only)
Stebro (muffler only)

Exhausts for 06-08:
Supersprint (muffler will fit but it won't look right, but their headers, cats, etc "should" bolt-up)
Eisenmann (midpipe & muffler - also offers a dual outlet but requires new bumper)
Bastuck (midpipe & muffler)
Arqray (muffler only)

I might be missing another brand or two, ie I think Remus also offers a muffler for 03-05 but this is pretty much the whole list. And in terms of headers, Supersprint is the only brand I know of that makes headers for the N52.

End of day though, if you're looking to hit 25-30hp increase, exhaust and filter won't be the way. You're better off spending that same money on headers and high flow cats (both and ONLY offered by Supersprint). Then get a software upgrade, and ask if they can customize it around the fact you have headers. You can get ALL this for the same price you'd pay for getting a dual exhaust (conversion) & new bumper, so it's money better spent in my opinion.
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      01-14-2011, 11:52 AM   #14
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Quote:
Originally Posted by Dubbedown View Post
The only exhaust that I know of that fits the 3.0si is Bastuck. Supersprint offers one but last time I checked, it was really meant for the 03-05 models, and thus does not fit well on the 06-08 models (it will hang too low). Arqray also offers one specific to the 3.0si but it is only a muffler.

The only software upgrade I am aware of is Active Autworks and Gintani although if it were me, I would go with AA (seems like based on recent reviews, AA has smoother power delivery although Gintani might offer more peak hp). Expect around 8hp increase for both tunes.

Filters, not really much out there besides Afe but they get mixed reviews, (check e90post under the NA tuning section). I'd stick with the oem box and just replace the paper filter with something else. I used to have great experience with ITG Air filters but I think they only have something for the m54 engine. I asked about 06-08 Z4s and they redirected me to the 03-05, saying it would fit but I was skeptical.

Exhausts for 03-05:
Supersprint (everything available, from headers down to muffler)
Milltek (midpipe & muffler)
Bastuck (midpipe & muffler)
Eisenmann (midpipe & muffler)
Dinan (muffler only)
Stebro (muffler only)

Exhausts for 06-08:
Supersprint (muffler will fit but it won't look right, but their headers, cats, etc "should" bolt-up)
Eisenmann (midpipe & muffler - also offers a dual outlet but requires new bumper)
Bastuck (midpipe & muffler)
Arqray (muffler only)

I might be missing another brand or two, ie I think Remus also offers a muffler for 03-05 but this is pretty much the whole list. And in terms of headers, Supersprint is the only brand I know of that makes headers for the N52.

End of day though, if you're looking to hit 25-30hp increase, exhaust and filter won't be the way. You're better off spending that same money on headers and high flow cats (both and ONLY offered by Supersprint). Then get a software upgrade, and ask if they can customize it around the fact you have headers. You can get ALL this for the same price you'd pay for getting a dual exhaust (conversion) & new bumper, so it's money better spent in my opinion.
!!!! Thank you very much for that info. I do have to say that the dual exhaust conversion would be mostly for cosmetic purposes, I just like the look. Anyway, that is just optional for now. I know of the Eisenmann's dual kit, but I wanted to make it split at the x-pipe, be a proper right exhaust, not just to split from the first muffler.

As for the air filter, that is exactly what I am looking for, a direct swap without changing the box. I have found, however, this filter: http://cgi.ebay.co.uk/ws/eBayISAPI.d...#ht_3236wt_905 but am not sure about the company. Anyone know if they are any good?

My car is December 2006 so I guess I will check the supersprint options and I guess I should be looking for a muffler that would fit their system. Just as well I might get one custom made if I do not find anything else.

Now we come to the chip. I have looked around a couple sites and on average they offer 20bhp. I hope that the AA chip would give an increase of over 8hp, especially when combined with the exhaust and air filter. In any case I do not see a reason why it would give less than the other chips. There are a number of local, to Bulgaria, companies that offer custom chips based on the specific car, however, I feel like I cannot trust them with my car, for some reason I feel like they do not know exactly what they are doing. One of the companies is called Digital Tuning, if anyone has heard of them I would appreciate some comments on the quality of their work.

I might actually contact Capristo to ask them about that custom 3.0si muffler they made for the guy in the youtube video.
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      01-14-2011, 12:15 PM   #15
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BTW, why do you say that the Supersprint muffler would not look right on the Z4?
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      01-14-2011, 03:31 PM   #16
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!!!! Thank you very much for that info. I do have to say that the dual exhaust conversion would be mostly for cosmetic purposes, I just like the look. Anyway, that is just optional for now. I know of the Eisenmann's dual kit, but I wanted to make it split at the x-pipe, be a proper right exhaust, not just to split from the first muffler.

Now we come to the chip. I have looked around a couple sites and on average they offer 20bhp. I hope that the AA chip would give an increase of over 8hp, especially when combined with the exhaust and air filter. In any case I do not see a reason why it would give less than the other chips. There are a number of local, to Bulgaria, companies that offer custom chips based on the specific car, however, I feel like I cannot trust them with my car, for some reason I feel like they do not know exactly what they are doing. One of the companies is called Digital Tuning, if anyone has heard of them I would appreciate some comments on the quality of their work.

20hp seems awfully generous and in general from my experience, you rarely see such gains on a n/a motor. Even 8-10hp is pretty good for n/a. You should ask for proof (Dyno charts) for whoever is offering 20hp gains. But AA is a pretty reputable company so I find it hard to believe that another tuner could give you double the gains. And if they did, it goes along with your initial concern about engine longevity. The only other thing I can think of is that the US Z4 has different emission standards so I know even as a baseline starting point, our cars put out 10hp less.

Quote:
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BTW, why do you say that the Supersprint muffler would not look right on the Z4?
Because I've seen it, and it does not look right =) Check the pictures below, someone else's car. He didn't seem to mind but I personally would not want this gap. Check Supersprint's website, IF they offer DIFFERENT part numbers on mufflers for 03-05 vs 06-08, then you should be fine. But when I last checked, they were offering 1 part number for both models, and one size fits all is NEVER the case. I assume headers should work b/c I believe they do offer different part numbers for 03-05 vs 06-08.

Also this sounds right because when I was first in the market for an exhaust, I encountered the SAME problem when I purchased my Stebro muffler. Those were originally designed for 03-05 and I was told by the company it would fit 06-08. Sure enough after attempting to install it, it hung way too low and I had to modify the hangers in order to raise it up. For the amount of money you're spending on a Supersprint, I would expect perfect or near perfect fitment. And FYI, I've compared the stock exhaust for 03-05 vs 06-08 and it's way different -- the piping diameter, bends, etc are all different so it makes sense that whatever's specific to 03-05 would not fit well on 06-08.
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      01-14-2011, 03:54 PM   #17
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Well I do have a long way to go before I get to chipping the car, for now I would want to concentrate of the other stuff. Can you tell me something about the K&N air filter I linked from ebay in an earlier comment?

I found this company called Akrapovic, here is a link of an exhaust on the 335i, too bad they do not make one for the Z4, this thing has a killer sound!!!!


Actually, on the Supersprint website there is a muffler with dual pipes which I believe is for the 06-08s, it is after all in the category saying: BMW Z4 Roadster / Coupé LHD 3.0si (265 Hp) '06 –›, so I reckon it should fit. Here is a link for the category, you can see the dual pipe muffler on the second row down: http://www.supersprint.com/USP0000bmwZ46.asp
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      01-14-2011, 04:23 PM   #18
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It's too bad Dinan doesn't make a 3.0si exhaust. The N52 330i exhaust sounds pretty good:

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      01-14-2011, 04:31 PM   #19
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Well I do have a long way to go before I get to chipping the car, for now I would want to concentrate of the other stuff. Can you tell me something about the K&N air filter I linked from ebay in an earlier comment?

I found this company called Akrapovic, here is a link of an exhaust on the 335i, too bad they do not make one for the Z4, this thing has a killer sound!!!!


Actually, on the Supersprint website there is a muffler with dual pipes which I believe is for the 06-08s, it is after all in the category saying: BMW Z4 Roadster / Coupé LHD 3.0si (265 Hp) '06 –›, so I reckon it should fit. Here is a link for the
category, you can see the dual pipe muffler on the second row down: http://www.supersprint.com/USP0000bmwZ46.asp
I'm aware of Akrapovic, at least coming from the motorcycle side... and yea, it's a shame they don't have something for us. In regards to the Supersprint muffler you're referring to, I think you should be a fine. Quick glance shows p/n:

2007 Z4 3.0si - 022 981 306 (Street Muffler w/ Round Tips)
2004 Z4 3.0i - 022 788 106 (Street Muffler w/ Round Tips)

Just make sure the same logic applies to the midpipe, etc (different p/n for different years).

Can't really comment on the filter as I haven't used it in our cars but I'm a firm believer the stock filter/airbox is pretty efficient. I only mentioned the ITG filter b/c its foam design allows more flow than stock but not at the cost of less filtration. But again, I'm not sure if they have a filter for our cars.

K&N filters typically require you to re-oil but if you overdo it, it could screw up the MAF. Of course, the flip side is don't screw up, and give the filter plenty of time to dry. But for me, the benefits of K&N filter wasn't better flow, or more hp but just the fact that you could reuse it and save money. I never really saw it as a performance mod. I think what you posted is a drop-in filter, which in that case might be comparable to the ITG filter.

If money is no object and you're trying to spend every dollar for ever last bit of hp, you could look into the Gruppe M filter, which is a carbon fiber enclosed box, but expect to pay $1200 for it.

Quote:
Originally Posted by pokeybritches View Post
It's too bad Dinan doesn't make a 3.0si exhaust. The N52 330i exhaust sounds pretty good:

Btw, if anyone cares I posted a brand new Dinan exhaust (muffler) for sale in the classifieds. End of day, a muffler is just a muffler and I highly doubt this Dinan is that specific to the m54 - it's really only from a fitment standpoint. So if you're OK with that, you could just buy that and have any exhaust shop mod it to fit, similar to what I did with the Stebro. Just modify the hangers and mate it up to your existing pipe... and that might require an adapter as well.
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      01-14-2011, 04:31 PM   #20
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heres what i have on my Si
Rpi intake scoop
K&N drop in filter (im assuming its the one you put a link to)
Stebro Muffler
Veizu Tune

Heres my take on all the items:
The Rpi intake probably gets most of that gain in power from removing the restrictive cup that partially covers the intake inlet, though im sure the scoop part does work
The K&N makes the intake louder and you can feel the engine breathing better, especially when paired with the Rpi scoop
the stebro muffler made a pretty big difference with my cars power and with the way the car responded. Its very loud at times, mainly when accelerating slowly from a stop. Made my intake suction sound louder as well after the install
finally the Veizu tune, the mid range difference is very large, alot beefier in the mid range so much so that you can feel the power taper around 6k.

keep the stock intake and do what i have done to it. once you do, the suction sound alone will convince you that the intake mods are working very well

on the exhaust: the stock muffler is HUGE, once taking that out there is a noticable difference in throttle response and an increase in power as well (i compare against a friends car every time i get a mod) Since you have the euro headers already the only thing to change would be to swap the cats with a high flow, i doubt increasing the pipe diameter of the exhaust will make any differnce as it has two pipes all the way through so i wouldnt bother with a full system. Our exhaust is different than the M by a great deal so i recomend going under your car and you will see what i mean.
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      01-14-2011, 04:35 PM   #21
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btw none of the exhaust for the si fit perfect from what i heard, that being said any reputable shop (with welding equipment) will be able to fit the exhaust perfectly, just with some work. On the stebro that i have the hangers had to be heated and bent to get the muffler to hang just right. You can see that is all that needs to be done to the ss muffler in the picture above, but to me a dual tip just looks much better. I have recieved many compliments on my exhaust from many different people. the sound is as good as it gets, but the in cabin sound is also probably louder than any other exhaust for our cars.
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      01-14-2011, 04:36 PM   #22
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Originally Posted by txz4 View Post
heres what i have on my Si
Rpi intake scoop
K&N drop in filter (im assuming its the one you put a link to)
Stebro Muffler
Veizu Tune

on the exhaust: the stock muffler is HUGE, once taking that out there is a noticable difference in throttle response and an increase in power as well (i compare against a friends car every time i get a mod) Since you have the euro headers already the only thing to change would be to swap the cats with a high flow, i doubt increasing the pipe diameter of the exhaust will make any differnce as it has two pipes all the way through so i wouldnt bother with a full system. Our exhaust is different than the M by a great deal so i recomend going under your car and you will see what i mean.
Aside from weight savings, I doubt the Stebro muffler gave you any gains. I don't even claim that my Bastuck midpipe & muffler yielded any gains. At most, you shaved few pounds and it increased sound. Thats why if OP is serious about hitting any hp #s, he shouldn't even bother with the exhaust and just go straight for the headers and cats, which is where most of the restriction lies.


Quote:
Originally Posted by txz4 View Post
btw none of the exhaust for the si fit perfect from what i heard, that being said any reputable shop (with welding equipment) will be able to fit the exhaust perfectly, just with some work. On the stebro that i have the hangers had to be heated and bent to get the muffler to hang just right. You can see that is all that needs to be done to the ss muffler in the picture above, but to me a dual tip just looks much better. I have recieved many compliments on my exhaust from many different people. the sound is as good as it gets, but the in cabin sound is also probably louder than any other exhaust for our cars.
I'd say my Bastuck is 97% good in terms of fitment, which in my experience is probably as good as it gets after having done these same type of modifications on other cars. The only thing I had to fiddle with was the crossbar on the left side, and had to put a slight bend in order to let the midpipe run without contact. Here some pics of what's included in the Stebro and how fitment looks underneath. I'll try to post some pics of how it looks on the car.









and how it sits (not the best picture but you see the tips are pretty flush and even)

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Last edited by 3002 tii; 01-14-2011 at 04:45 PM.
3002 tii is offline   United_States
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