X-Pipe vs H-Pipe

[71400lb]

Sorry if this topic is old, but I couldn't get anywhere with the "search" option.
Anyway, is anyone using an X, or H Pipe on their small block Chevy engines? How much horsepower and torque does each pipe gain? Is it worth it?

I have a 1971 Chevy Cheyenne C/20, 2WD, 400 SBC, 4 bbl, dual Flowmasters(quite ones, not sure what series), 400 Turbo Trans, 3.73 Open Rear end.

I'd like to add Dynomax Turbo's and either an X or H Pipe...any opinions for me out there?

Thanks All,

Rick
1971 Cheyenne C/20