you have a ZHP, why did you feel the need to drop it? why not leave it as is? modding a ZHP defeats the purpose of buying one in the first place since it's upgraded with a "performance package." it already comes modded from the factory. i'm not saying our cars are the "be all and end all" of the BMW lineup, which belongs to the Ms, but didn't you get a ZHP so you wouldn't have to mod...or mod as much?
with that said, i hope you get things fixed. doesn't sound like too much of a problem. i assume the shop did a wheel alignment after installing your new suspension? sounds like it might've been a subpar job causing an offset in the camber. this can easily happen if the wheel wasn't perfectly centered while the wheel alignment was performed. did you also install a camber kit?
Caster and camber, being different from one side to the other, can make the car pull. For example, you are going perfectly straight on a flat road and you let go of the wheel and it pulls to one direction. However, if the camber is the same on both sides I would think it is more likely a tire, caster, or other issue.
However, if the wheel has to be slightly turned to one direction or the other straight, but letting go of the wheel doesn't result in a pull, then the steering wheel simply isn't centered. It won't hurt anything, but it can be fixed by adjusting the toe. If, for example, one tire is toed in one half of a degree, and the other tire is toed out, the result is that it will actually track straight with the proper angles without pull. because of this, the steering wheel will be off centered slightly when going straight.
try to take it back to the shop and get it realigned.
Last edited by bouchet; 10-20-2008 at 12:48 PM.