"Lower intake manifold houses secondary runner butterfly and fuel injectors along with fuel rails. Below 3700 rpm the engine only breathes through primary runners and one intake valve. At 3700 rpm a 34 mm butterfly opens and allows the engine to breathe through both intake runners and intake valves." From SHO.com. I guessed with it being open, you get more power. If you don't understand, don't worry about it (for now). Someone, (Ray maybe) will give you a better description later.
As for the plugged exhaust (aka catalytic convertor being broken and plugging up the exhaust), sometimes, a clogged catalytic convertor can cause bad engine performance at higher RPMs. For now, don't worry about it. Just test the IMRC and go from there.
Edit. Any CEL codes?
Might be good to go to the library and pick up a car repair book or manual (Chiltons, Haynes or Popular Mechanics) to read up on how cars perform. Good luck.
Last edited by Tony2005; 11/01/05 05:41 PM.
