From what I understand a 75mm is a little too big if you don't have forced induction, so that maybe what your problem is. I went with a 75mm myself because I plan on going forced induction and didn't want to have to go get a bigger t/b later. I'm sure others will chime in, but that's what I was told.Has anybody every experienced tourqe loss after installing a 75 mm t/b plenum combo? I was wondering if I was to mess with the air to fuel ratio with the sct if I could curve this a little. Anybody got any ideas, or suggestions?