Hey, motor guys.. Ok I got stock twin 454mag MPI's in my 312Formula.. I have Gill offshore Exhaust and Vortech MPI Breathers.. I want more oommff and some top end. Some say that the stock heads on these Mag MPI's (roller cams too) are good to port, pocket and put larger valves in.
Or should I just go with an after market Alum head set up Like CamField.
anyone know of some good set ups, valve sizes etc. even cam info

Not looking for a race motor dependable power.

Tyler Crockett has a nice upgrade for your motors. I had his shop install the upgrade on our boat and really like it. The kit includes cam, ecu flash, 2.25 intake valves/1.89 Inconel exhaust valves and Stainless Marine exhaust. You already have the exhaust so the parts should not be that expensive. The engine sounds and runs significantly stronger. Our engine dynoed at 461HP 5100rpms and 514lbsTQ 3800rpms. Check out the upgrade specs on his website: crockettmarineengines.com

those are stock rectangle port heads on there ?
if so
you can spend a little money on them and have them ported and worked over, they will make some good power for you if done correctly and setup with the proper cam and valvetrain

go with a custom cam from Bob Madera at Marine Kinetics well worth the money, just give him your engine specs and power goals and he will take care of the rest

if you need any port work done I have a local guy who is great at it, if you want pm me i'll put you in touch with him,

this will probably end up being cheaper than going with aluminum heads, especially if you have 2.19, 1.88 valves in those heads already (which you might have)

A reflash of the ECU is essential.