"H-pipe," X-pipe," or no pipe?

I've mentioned this before in another thread. I read this in a car mag or article somewhere a long while ago. They did a dyno test between the three. No crossover, X pipe, and H pipe. I don't remember numbers, but the X pipe made more peak power, and the H pipe made more torque over the X pipe. When I built my own H pipe I could definitely tell a difference on the low end and it sounded better and quieter in my opinion.