OK here is the scoop. My husband has run extensive dyno tests on his dyno using mufflers on his superstocker, my street car, and almost every engine he dynoes. How much the muffler flows means nothing. If you want flow, then take the entire exhaust system off. It is the speed at which the exhaust flows that counts. My car has stock exhaust manifolds, 38" of 2.5" pipe and supertrapp mufflers with 28 discs each. The dyno said that was optimum for my combo. It made more power over open pipes and more power over flowmaster 40 series mufflers. My engine makes power to 5500rpm and is a very mild street engine. The length of the pipe from the manifold to the muffler is a key point that is always forgotten. Your big power loss is not in the exhaust which is always easy to blame much like carbs. and ignitions. My guess is that it is a little bit of everything that is wrong. Also, open exhaust rapps up fast when you hit the throttle, but doesn't under a load. I have heard thousands of drag cars sound like prostockers in the burnout box but are terds off the line:rolleyes:.