> My thought, > Detonation. What you may be feeling is the power fall off when the knock > sensors pull timing. I've felt the same on other knock sensored turbo > cars. > And since you do feel it when you raise the boost then they may be > connected. I'd agree. I had to retard timing significantly to stop this effect on the MC engine. It would just feel soggy over about 4800 rpm. Orin.