Originally Posted by richie_s999
you want to find a 4.27 diff, not easy but worth it, and get a Mark D chip, he's on the baord, just go with an e36 rack, its a lot cheaper and easier to find then an M3 one, and only .2 turns different. Stay away from the z3/4 rack, only reason its shorter is cause it doesn't actually turn as much as an E36 one.
I did some reading after we talked about this at Downsview, and I believe this is not quite correct. The 2.7 turn z3 rack *does* turn less, but that's not the only reason it's faster. It is just as fast as the '95 M3 rack, but you get less final wheel deflection, hence the quicker lock to lock. So Ideally a '95 M3 rack, but if you are tracking the car a Z3 rack is just as good... if you are doing U-Turns in the city and tight autocross circuits the 3.2 turn e36 rack might be better because you get a tighter turning circle than the z3-- but not quite as quick a ratio. Dig?
I have no solid sources for this on hand but thought I would pipe up anyway.