check the insulator between the steering shaft and rack & pinion, or the bearing that is on the steering shaft at the firewall.
RC- a PHB keeps the rear end centered, I dont have one but i hear it's a very good upgrade
I was doing some more research on it, and more than one person suggested AGAINST it unless you do a lot of racing....that it makes the ride really rough.
Dont know if that' accurate or not

RC