I am currently having a redone S4 T2 engine put in my car. Previous work had me upgrade to a S4 turbo tranny awhile back with a lighter flywheel. We jury rigged it to run with the N/A rear end from my S5 N/A by redoing the bolt pattern on the driveshaft.

I am currently estimating said and done to be running about 265-270HP. What are the HP tolerances for the S5 rear end of a 90 GXL?