i also have a screeching noise but only at higher boost(anything over 10lb), but i don't notice any loss in perf. by the way my mechanic recently did a rebuild & suposedly replaced everything that needed it. o yea, it started after an autox at buttonwillow

same with me, we seem to have similar problems, plus I also do not notice any power lost. but really want to find out what the sound is. my rotary mechanic told me it could be the main cat being clogged, but i don't think a clogged cat can make such noise.

well it cant be the cats because i dont have any. my mechanic told me that it could be an exhaust leak, but i think it is my stock blow off valve.