How often do you guys change your spark plugs. Also whats recomended for 502 efi gen 6 Thanks.

once a year for me.

in most cases it should be at start of season after firing up and burning off the fogging oil, in the case of the 496 with platnum plugs 85 - 100 hrs is what merc recomends

Delco mr43t's is what I always used in mine. 100 hours or so is probably ok.

thats way too many hrs for those plugs

MR43T is what you need. I change mine once a year, I have a 500efi.