size & "H-pipe"

Mild street 440 4bbl...question is should I run 2 1/2 or 3in exhaust? Tri-Y Schumacher headers is what I already have. Also should I install a "H-pipe" ? What does it do? I've heard both yes & no about a "H-pipe". Thanks

Schumacher's have a 2.5 collector. That si the size exhaust you should run. X pipe is best, H pipe is better than nothing.