i have seen were the 500 efi has been upgraded to 625hp by Ron Potter and others. What is the correct combination to do this or more?

Don't bother...I did it, won't do it again. We didn't use anyone's "kit" but built our own (a couple buddies were the knowledge behind all the checks I wrote).

Made 540's out of the bottom end, ported Iron Eagle heads, BIG cam, 9.7 compression, monoblade ASM throttle body. The intake will hold you back. Dyno runs from seawater pump to my wet CMI's made 630HP and 700/ TQ. HP would have been higher (maybe 30-40) if we had went to carbs since the motor can't get enough air through the plenum. I was told all this but insisted on going EFI....It runs good but cost a fortune by the time we were done.

If you had started with HP 500's carbed to start with would you still say you would not do it again?

i know they changed the cam and heads, bumped the compression up and mapped the computer. left the motor a 502. ijust read on other thread Tyler Crocket was working on a new intake.

I have a new plenum top that will fit right on your intake manifold with a 2000 cfm throttle body built flush right in the top so the air will go right down the runners with on restriction. I plan on having one at the Miami Boat Show in Feb.

The main problem with mine is that we cannot use everything in the bottom end since we're not getting enough air. A buddy built 540's the same time I did and he had carb'ed 500's. Putting a bigger carb and air breather on his intake solved that air flow problem for him.....so yes, I'd do it again with a carb'ed 500.

do you offer a kit to get to 625 plus hp? how much? best time and way to contact you?

PM Thunderstruck. He has twin 650 hp from 500's and did the work himself. He's knowledgeable about it.

So Russ, you ended up going to carbs right? We'll talk in a couple of weeks.

I have a kit we have done several of these. Shop # is 8103242720 9-6