Stock 90 vette, really sounds great, my biggest fear was drone and on mine the only hint of drone is around 45-50 just prior to shifting, running at 70+ no drone I did have to cut one of the enclosed pipes for it to fit, I called Borla and they said they were different lengths but I could not get it to fit, swapping pipes it worked fine so I cut 2 inches off the left and fit fine. The exhaust runs straight down the center so not sure why one would be longer, seems like it may be offset on some of the other c4s I have owned, anyway despite that worth every penny.