Where's the proof (X-pipe vs. H-pipe)?
 

I've heard on this site quite a bit that the X-pipe produces more peak horsepower than its cousin, the H-pipe. That's all well and good, but I've got to ask, has anyone ever proven this with dyno graphs or timeslips? (Preferably dyno graphs, since there are a little fewer variables involved). I understand that there's not a whole lot of difference either way, but just for fact-finding purposes, I'd be interested to know.