Convert HP500efi to 525
 

Would it be easy to do?

It would be pretty hard to my understanding, they have different eletrical systems and some other stuff:rolleyes:

As for upping a 500efi to a 525 HP Arizona Speed Marine makes a kit for it, But I have heard it was not worth it, no noticable gain??:rolleyes:

I wouldn't see any reason to do so, totally different ignition, new exhaust, new heads, closed cooling, etc for 25hp? Recal the ECU and put a bigger throttle body for 20hp, it's a very little difference so might as well do it cheaper. You could even supercharge it for cheaper than converting, just run 1lb and you'll make 540-550hp :D

Dustin