Originally Posted by Shagdog
One more thing... Looking at your picture a little closer, Your exhaust may not be enough. Open that third exhaust port up. If you cut 1" holes then your pipe is 3/4"? That give you less than 1 1/2" worth of exhaust by the time you look at the ID of the pipe. I would keep all 3 wide open the whole time you have it running. Too much exhaust is better than not enough.
I agree with the "not enough exhaust" theory.