X or H cross.

I have TTI headers, their 3" X-pipe and Dynomax UltraFlow mufflers on my race car. Car picked up and I'm sure the mufflers didn't hurt. (Minor rejetting may be required for best results.) I didn't do a comparison, but I never even considered an H-pipe. They both balance the pressure, but the X-pipe would seem to help balance the flow and help each side scavange the other with more constant alternating pulses. I recently saw a good explaination somewhere but don't remember where! :(

I've gotten lots of compliments on the sound but don't know how other factors affect the sound, like cam duration.