It's a pressure thing. The X or H pipe helps to even out the back pressure. I noticed a change on my truck when I redid it with identical runs. If the pipes are bent in identical runs and constructed of the right size pipe,(not too small, not too big), than I can't see any reason to having either. I think they are more useful on systems with asemetrical bends,like on a 4x4, etc., where the pipes have to be routed differently.The vette allows for semetrical runs under or along side the car so like I said I don't see any reason for them,......but I'm no expert. Maybe you could PM Mech259, I would value his opinion. Too bad Lee Willis is nolonger a member, he would have an answer as well. Cheers
God Speed Rich.
"I've seen monkey Sh!t fights at the zoo that were more organized than this" ......
I haven't had any vehicle with a cross-over but the way I understand it the exhaust pulses from one bank help scavenge the other bank through the cross-over, even with equal length duals it is supposed to have some benefit.
I think 78buckshot hit it on the head. I also remember reading where to properly position where to put the "H" pipe, you need to put temp sensitive paint on the exhaust pipe. This is where it gets a little foggy (destroyed too many brain cells in college and the Navy [sm=icon_guiness.gif]) but you either put it at the hot spot or cold spot.