Z4M Stock exhaust modification.

[tikamak]

The thing is that I love the stock Z4M sound and I feel that it sounds much more furious than any aftermarket exhaust maybe except the super sprint race exhaust.

Have anyone tried to mod the stock exhaust like on the e92 M3 forums to make it just louder without loosing it's tone? Maybe add a tube from the inside of the helmholtz chamber to the outside and stick a manually controlled valve on the top to control the level of loudness?

I had a drift event last weekend and my friend had a supercharged M3, with section 2 and exhaust removed to make the car loud in the event and save weight and the car sounded like a pissed off CSL. I loved that sound and i felt that it was very close to what the stock Z4M sounds like in terms of tone, not loudness.

I would love a DIY if anyone experimented with this. I would sure love to keep my car's sound just louder.

[ZStig]

Someone removed the stuffing inside the stock muffler, with no improvement in sound. If you wanna keep the sound, you can change the headers to give it more rasp (but not a lower tone), or remove the cats

[mfanatic325]

The largest sound difference (changes the "character" of sound of the car) will come from the mufflers. Fiddle around with that. A lot of people that aren't willing to shell out hundreds and thousands for these pricey exhaust systems make do with muffler deletes. Essentially removing the OEM mufflers, and fabricating a connecting pipe with tips in the mufflers' place.

I made a thread with some HD videos of when I was originally swapping out my mufflers with SS Race, and I was curious about how the car would sound without mufflers during the install process. Look up some threads I've created before, and you should be able to find it.

Muffler delete is a much more affordable alternative if you want to improve the sound. Just be aware that removing the mufflers altogether may make your car too loud to local authorities, so be careful how you drive near/around them

edit: found the thread for you http://www.zpost.com/forums/showthread.php?t=430901

[tikamak]

I read the threads and posts and i loved the sound very much.

I think that it is a bit loud though, i wanted to see if someone experimented with fiddling with the mufflers for maybe 25% higher volume and agressiveness.

I am sure looking for a very cheap option, the Z4M stock sound is the best IMO, very balanced sound with character, just not loud enough to scare away japanese ricers :P

[mfanatic325]

If that's the case, then perhaps look into replacing your section2 exhaust piping (a.k.a. x-pipe). It'll help you gain a few horsepower also. But you're looking at spending about $500 USD for a new aftermarket x-pipe.

Just replacing the x-pipe alone might be a big enough increase in sound for your needs/tastes

[BTM]

If you like the stock tone but want it to be louder, you could gut your section II cats like I did. It literally sounds just like stock, but louder. Labor intensive, but a cheap DIY (only had to buy some BF drill bits, and beer)

[inTgr8r]

Originally Posted by BTM

If you like the stock tone but want it to be louder, you could gut your section II cats like I did. It literally sounds just like stock, but louder. Labor intensive, but a cheap DIY (only had to buy some BF drill bits, and beer)

He has a Euro car, so he already has one set of CATs less than us.
That's probably why he likes the stock sound.

[tikamak]

I have a US car, i bought it from a manheim auction in CA, shipped it to LA and then to Lebanon Beirut.
Cost me 13750$ customs, overall 47500$ Z4M Roadster 2006 Tiag/Black

I like the tone a lot but i still feel that my car/car sound is being suffocated from the cats in the (f***ing) US headers and section 1 and Xpipe, i will be getting some e46 M3 CSL headers or EURO headers or maybe SS stepped V2 in the future and just leaving 1 set of cats in the section 1 for CEL elimination.

Personally I would absolutely love to run a straight pipes all the way + tune to eliminate CEL, authorities would love it here instead of pulling me over (yeah i know it's fucked up)
Unfortunately i think it is way too loud for the passengers and my prestige :P lol

I would just be cool with maybe 40% more loudness and aggressive tone and accompanied by and RPI scoop in the future and a VT2 in farther future.

I will remove the cats in the XPIPE as a first step, no point in investing in aftermarket since the XPIPE is high flow enough for the S54 and present the highest hp figures (without cats) IMO. the headers are the bottleneck in our cars, my 2 cents.


What i was ultimately thinking is to gut the mufflers and introduce a pipe from the helmholtz chambers to the outside un muffled and introduce a wireless controlled valve device to change from stock (fully closed valve) to straight pipes (fully open valve) and in between.

If anyone in here have gutted their OEM Z4M muffles and took pics, please share them with me, it would help me a lot to know how the muffler looks like before i gut it "inproperly"

[tekmoe]

Rather than modify the stock mufflers, why not try and pick up a used pair or better yet, just get some Magnaflows like I did and mount some badass tips on them. Sounds great and costs way less than any aftermarket exhaust system. Runs just as good too.

[tikamak]

I don't want to spend a dime considering that the OEM exhaust is a very great system and i think the highest potential gain can be achieved with stock parts and some modifications.

by the way, just help me out with the terminology because online posts are confusing the shit out of me:
primary headers are the ones in the section 1 exhaust (not headers)?
secondary headers are the one in the xpipe?

[tekmoe]

If the OEM exhaust is so great, why are you trying to modify it? Makes no sense.

[BTM]

Originally Posted by tikamak

by the way, just help me out with the terminology because online posts are confusing the shit out of me:
primary headers are the ones in the section 1 exhaust (not headers)?
secondary headers are the one in the xpipe?

The headers are the first part of the exhaust, bolted directly to the engine. They have the primary catalytic converters, which is where the pre and post cat o2 sensors get their readings from. Just behind this is section 2, which contains secondary catalytic converters, with no sensors - these can be deleted without problems. These are the cats I gutted. The x-pipe is bolted behind this, and does not contain any cats.

[tikamak]

Originally Posted by tekmoe

If the OEM exhaust is so great, why are you trying to modify it? Makes no sense.

My point was that the OEM exhaust has high flow enough to be equal to most aftermarket exhausts in terms or HP and torque. At least so I've deduced from many posts and discussion about exhausts. Please do correct me if i'm wrong.

I just want to remove the restrictions and make it louder, no intention of modifying it for power.

... at least for now :P

[tikamak]

Originally Posted by BTM

The headers are the first part of the exhaust, bolted directly to the engine. They have the primary catalytic converters, which is where the pre and post cat o2 sensors get their readings from. Just behind this is section 2, which contains secondary catalytic converters, with no sensors - these can be deleted without problems. These are the cats I gutted. The x-pipe is bolted behind this, and does not contain any cats.

Question 1:
Is your change destructive? can i plug the cats right back in if i ever decide to go EURO headers + section 2 relocated O2 bungs ?
Tell me how does the car feel after your change?

Question2:
Is it possible for someone to remove all cats in his car and do a tune (ESS?) to remove the CEL?

Question3:
What is this thing in the Xpipe? the resonator? what does it do and why aftermarket exhaust Xpipes remove it? does it create any extra rasp to remove it?

[GP20]

Originally Posted by tikamak

The thing is that I love the stock Z4M sound and I feel that it sounds much more furious than any aftermarket exhaust maybe except the super sprint race exhaust.

WTF.

[tikamak]

Originally Posted by GP20

WTF.

I meant straight pipes with stock headers and section 2 and X pipe :S

My friend has this with EURO headers. Can't beat that hellish sound really. Sounds like an F1

[johanness]

3) yes, if u remove it, expect more rasp. More so if u have headers.

[BTM]

Originally Posted by tikamak

Question 1:
Is your change destructive? can i plug the cats right back in if i ever decide to go EURO headers + section 2 relocated O2 bungs ?
Tell me how does the car feel after your change?

What I did is irreversible - took off section 2 and drilled out the media from the cats. The only way to put it back would be to buy a new section 2 piece with cats that are intact. You could always replace this section with straight pipes, or straight pipes + resonator, keeping your OEM section 2 intact

The car sounds like stock, just louder. Were you to go with just straight pipes, I'd think it would be louder than how I have it. Considering how the empty cats now act as pseudo-resonators, not sure how it would compare to an aftermarket resonated setup. It may have freed up a few horsepower, though this isn't really noticeable. It does seem more willing to rev in the 3-5k range

[zubydafa]

Originally Posted by BTM

What I did is irreversible - took off section 2 and drilled out the media from the cats. The only way to put it back would be to buy a new section 2 piece with cats that are intact. You could always replace this section with straight pipes, or straight pipes + resonator, keeping your OEM section 2 intact

The car sounds like stock, just louder. Were you to go with just straight pipes, I'd think it would be louder than how I have it. Considering how the empty cats now act as pseudo-resonators, not sure how it would compare to an aftermarket resonated setup. It may have freed up a few horsepower, though this isn't really noticeable. It does seem more willing to rev in the 3-5k range

just searching around for some exhaust options. i'm leaning towards getting the RE xpipe first. if i'm not happy with the sound increase then i may have to pull the trigger on the el diablos also.

you said you removed the cats in the section 1 piping. care to elaborate on the resultant sound? i may look into doing that to complement my x pipe...

what do ya think?

[BTM]

Originally Posted by zubydafa

just searching around for some exhaust options. i'm leaning towards getting the RE xpipe first. if i'm not happy with the sound increase then i may have to pull the trigger on the el diablos also.

you said you removed the cats in the section 1 piping. care to elaborate on the resultant sound? i may look into doing that to complement my x pipe...

what do ya think?

With the stock exhaust, it's just like I said, sounds like stock just louder. Same tone, no drone, etc.

The exhaust I have now (BMS xpipe Magnaflow mufflers) I bought from a local forum member so I had the luxury of going for a ride in his car to hear it and see if I liked it. I ended up buying it, and on my car, it is a little raspier and certainly louder than it was on his car. Given the only difference between our setups was my secondary cat delete, I'd have to attribute it with the difference in sound. FWIW, it's louder than RPIs, so if you're worried about going too loud, I would mess around with the xpipe and mufflers first, because once you gut the cat it's gone and not cheap to replace.

I did also end up using a minimal amount of dynamat on the floor of the trunk to absorb some sound and vibration.

[Kgolf31]

So wait, let me get this straight...

Removing the Section II and replacing it with an aftermarket X-Pipe will remove your cats? I thought Cats were in the headers?

Just concerned, because my state requires emission testing...and they visually check for cats. Just didn't know if i'm only restricted to replacing the rear cans

[BTM]

There are 2 cats in your headers, and 2 secondary cats (with no O2 sensors) in the section between the headers and the xpipe

Replacing the Xpipe doesn't delete any cats. What I did also didn't change any of the emissions equipment since there are no sensors there. You'd have to take the pipe off the car to know there was nothing inside the cat