H- or X-pipe in exhaust

[MadMax]

Hi Folks,
I'm just building a new exhaust for my van and I want to go stainless steel for durability. Now I've heard (some muffler firms say that) that you should weld in an H- or X-pipe before the mufflers (my van has full dual exhausts without any connection between them).
What good does that do? How does it affect sound and performance? Or is it Voodoo?
Thanks a lot,
Mad

[billlsbird]

Max, I read on a Camaro web site that they both help performance but the 'X' helps performance more & the 'H' sounds better.... Or do I have it backwards??? Bill

[R Pope]

Either one helps power a bit by allowing pressure from one pipe to vent over to the other. Which you use depends mostly on room, the drive shaft is usually in the way of a true X. The crossover pipe is also easier to plumb into an existing system. The sound will likely be mellower, with less "snapping".