has anyone had success supercharging 7.4MPI's... I bought a 312Fastec with 7.4's, the dealer promised over 70MPH stock... didn't happen... now I hear you can't supercharge unless you have Mag's... can the 7.4's not handle the charge?

I'm no expert, but I've heard that the mags have better internal parts such as crank & pistons. (C-spray might know better)

How much speed are you getting now? If your motors have low hours, maybe you can upgrade to 502's or even 500hp's and sell you 454's? (Just a thought)

Toolman

low boost around 4 lbs.
Do not exceed 5000 rpm.
Expect a 100 horsepower gain.

That's about the reasonable limit for cast motors.
You can get a lot more hp from them by adding better heads and cam to the above combo but you're pushing your motors comfort zone by doing so.

The MAGS definitely have better parts, but the Mag crank is good to 750hp, the rods to 6500rpm, the pistons to 10lbs boost, the heads are better, and they are cammed better.

What you got will live a happy life at 440hp and 4900 rpm. No need for overkill here.

thanks for the info guys, bill