Jim R.

Wheel hop......... I had it bad prior to the SC, but now it spins the tires so hard, there is no wheel hop. Suspension is bilstein/eibach, hopped before the SC with the new and original sport suspension. I've used 2 sets of wheels and tires without any hop now-255/40/17's and 295/30/18's on Fikse FM-10's. Wheel hop was so bad I always was afraid of breaking driveline parts.

Drag radials would help, but not great for the clutch or cornering.

Jim R.

IcemanG17

Can a PSD diff be retrofitted to an S4? Or is upgrading to an LSD my only option?

John Veninger

Anything can be done...but the cost and time make it an option not to consider.
Your best bet is the LSD for your 88.

FYI- All 928 S4's/GT's/GTS's came with PSD from 1990 -1995.