My MP heads flow 430 cfm w/ the stock size valve. The Edelbrocks are a great head, especially for the money. I spent over a grand having MCH cnc port my MP heads. Wish they were available back when I built my hemi, but there weren't as many options back then.

CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax