I started with AFR 305s, 741 cam with a firing order switch, 55lb high impedance injectors and tune. do not use the stock 500 efi fuel system, you will lean it out and do lots of damage.. if you are interested in all the stuff i have i had it listed for 2500 per set.

To the OP, I have a pair of Vortech Superchargers for 500EFI if you're interested in going that route vs. Whipple.

Offshore, would you be willing to sell just your mono blade throttle bodies? Also, were your intakes honed out at all, or stock? Just curious as my 500's already have upgraded fuel system and cam with firing order switch. Im basically just planning ahead for when its time to do top ends, only have 200hrs on full rebuilds. Thinking a good set of heads and mono blade TB's and I should make some good reliable power.

id rather sell it all as a set

I looked into rebuild/upgrade of my HP500EFI's a while ago and ATECO looked pretty good. There should be a thread here if you search for "ATECO HP500EFI". Haven't pulled the trigger yet. Don't know if they still offer the package but it claimed dynoed results in excess of 600 hp, as I recall. Without force-feeding.

https://www.offshoreonly.com/classif...ds-o74373.html

in reality the 500 efi with some tuning could make 530-540hp so their claim of 125hp gain is some what miss leading, and to get 635hp through the stock TB and intake is almost impossible.