502 Efi
 

Lots and lots of people have made 502 EFI/MPI's run well. My build included long through transom Stainless Marine pipes, good Crane cam, Crane roller lifters and rockers, pushrods and springs, oversize Inconel exhaust, stainless intake, minor bowl work in heads, reprogram ECU, added RACOR filter after standard Merc fuel filter. My motors were VST and I ran in to a few debris problems with the standard water separator/fuel filter with the VST screen. 450 hrs trouble free so far. Replaced top end components @ 250 hrs. Sounds very nice, idles well, good power. Much less $$$ than a Merc HP500EFI with similar if not equal power.

A very good engine to work with, I believe. And, there are lots around nowadays and good deals are around.