[DeTomaso] X vs.H pipe commentary . . .

[MikeLDrew at aol.com]

Durango Dave asked about an H-pipe in 180-degree headers.

Uh...no.   At least, I don't think so.

Exhaust systems are compromised, and most cars with dual exhaust have all 
the left-side gasses exiting out the left side, right-side gasses out the 
right side.   The H- or X-pipe is an attempt to merge the two exhaust streams 
and take advantage of the scavanging effect from non-adjacent cylinders.

180-degree exhausts use a completely different system; they are enormous 
and complex, and are basically the H- or X-pipe taken to the fullest extreme.  
 Pipes criss-cross this way and that in a somewhat scientific attempt to 
fully realize the benefits of such scavanging.   So, if you have 180 exhausts, 
essentially you already have an H- or X-pipe design--in fact much more so.  
 Adding another pipe wouldn't do anything (or at least, wouldn't do 
anything good).

Or so it seems to me--somebody tell me if I'm wrong!

Mike