Let's start with the idea that there is no exhaust pipe or muffler in the world that can add power after a good header. The best you can do is come up with something that's transparent. That's why I'm using a 3" system.

Unfortunately, my system is not transparent in the midrange. It's mistuning the header in such a way that shockwaves from the exhaust (not the exhaust gases themselves) are blowing the intake mix back out the carbs. It then gets sucked back in with a double charge of fuel.

John Parker tells me he's had this same problem on several racecars, and the fix is to change the length of the exhaust. This makes perfect sense.

(Mike, apologies for hijacking your thread...)