Has anyone ported stock magnum heads and have the before and after flow numbers .???

Rat Bastid said
Look at CFM/CID. Just because you have 270 CFM doesn’t guarantee you 540 HP. Especially on pump gas with the de facto way too low pump gas compression ratios.

pittsburghracer said
And keep in mind if you have a head that flows [email protected] and run a .520 lift cam good luck hitting your number.