Ok. I did some research. Here is what I found. The purpose of H and X pipes is to reuduce the pulsing and back pressure of exhaust from 2 cyl's that fire at the same time on the same bank by bleeding the exhaust into the other side where there is no pressure. That helps torque and hp. The X pipe is more efficient and gives more torque and hp than the H pipe. The H pipe is louder. The X pipe has a lower smoother sound. So if you want sound go the H pipe, if all you are worried about is performance then the X pipe. I decided the X pipe. So now my question is who offers the best X pipes?