next upgrade?

[techno10]

I have 03 e85 z4 convertible. It does have a sport button so I'm assuming it's got some other sport features. It's a 6 speed which is great.. So far I've done:

1) magnaflow exhaust from mighty muffler (someone has a video on it on here). The install was nice, it's sounds good (some drone but I don't drive this car very far). But if I ever want to take it out I'm gonna have to cut it out.
2) m steering wheel and shift knob (these are fun upgrades tho expensive)
3) bought vmr v710 wheels. Same size as stock (18).. I weighed them with non-run flat tires and they were 8 pounds lighter than stock with runflat. Kind of worried when I go for longer trip at this point tho. They look nicer than stock and the lighter weight is great.. Not too worried about the finish and I got them used at an ok price. So for what I paid it wasn't a bad deal.
4) Bought a K&N filter and a small 10% down bend pipe and have a new intake (nothing special but fun).

So I was thinking of going 1 more upgrade fairly soon.. I'm leaning towards a LSD first.. later on (maybe in fall) I'll look at suspension next (single adjustable coil overs for sure). Ultimately I want to get a supercharger but we'll see.

So anyone have any ideas about the following:
1) should I go LSD before suspension (coil-overs?)..
2) if I go LSD where can I buy and which one should I look for? I do like acceleration over top speed (0 to 60 is more fun to me, etc). I'm going to try to do the install myself so what other parts might I want (going to do install and I'm a bit of a noob so new bushing might be out). Also I don't necessarily want to go completely acceleration but I definitely want to feel as tho it was an upgrade.
3) someone sell me a supercharger cheap

thanks,
Mike

[techno10]

pitty bump.. I guess I'm leaning more towards suspension upgrade. I'd really like to get coil-overs but I'm worried I'll drop the car too low. It already barely hits exhaust over some dips. Is there a different strut tower bushing so the car doesn't drop much?

leaning towards the H&R Coil Over Suspension setup but it seems to drop the car soo much.

So the car has around 54k miles on it. Would anyone recommend LSD over the suspension? Thoughts?

thanks,
Mike

[jeebus87]

At 54k miles, and more importantly after 12 years, your suspension could probably use a refresh. That gets my vote. I have Bilstein struts and love them. Some people go with Koni adjustables. H&R are an excellent brand so you can't really go wrong with those either.

[Steeler]

I just installed a pair of front spring perches on my daughters 2.5 to give it a bit of a nose down attitude. http://www.supremepower.com/suft015-...ml?mfg_id=1053

Seeing as you have sport suspension already the 5/8" or so that these perches drop will not give it a huge drop but will give it the lowered look you are looking for.
The parts are of heavy gauge steel and of very good quality.

As far as coilovers go you can lower as little or as much as you want. Not infinite adjustment but I am sure you could find your perfect drop setting.

[Cyclops]

Before the super chager go for the 3 stage intake with tune. Best bang for the buck. 25-30hp gain for less then $1k.

[pokeybritches]

There are several types of limited slip diffs, but the most common are the clutch type and torque biasing. There are advantages and disadvantages to each. I'm by no means an expert, and there's a lot I don't understand regarding ramp angles and clutch packs.

Clutch type LSD's have static lock built in, meaning the wheels are always locked to a certain degree (usually 25-40%). They are slightly noisier and more maintenance. Most track enthusiasts go for this type of diff. You can choose different locks for acceleration and deceleration, which changes the car's behavior when powering out of a corner or braking. Diffsonline and Performance Gearing are two places to source these diffs.

The torque biasing diffs multiply the torque from one wheel to the other using a special set of helical gears. I haven't driven a Z4 with this type of diff, but most owners who have made the switch say there is no increase in NVH. The car will behave exactly as it did before under deceleration, with no increase in understeer. Because torque is multiplied (usually 4:1 or 5:1), if one wheel has no traction, the diff behaves like an open diff. So, if one wheel is on ice or airborne, you won't put down any power (though some manufacturers, like Wavetrac, claim to have found a way around this). The install can sometimes be easier, as in certain cases the LSD will drop right into the existing carrier without much modification. Other times it can be a PITA. If your car is primarily street driven, this might be a better option for you. Quaife, Wavetrac, and now M Tech (I think that's the name) all manufacture torque biasing diffs.

I'm not set on which diff I will go with, but I'm leaning towards the former.

As for gearing, I love my 3.64 final drive. Stock was 3.07, so I see about 18.6% more torque to the ground with the same reduction in top speed in each gear. If you plan to get a centrifugal supercharger, this diff pairs well. However, if you want to get a positive displacement blower (ESS twin screw), a 3.64 might be too much. Click the link in my sig for more info. It directs to my build thread.

[pokeybritches]

And to answer your question, I would do coilovers first. There's a lot to be said about moving to linear springs and quality adjustable dampers.