I had antique GenV 502MPI's in my last boat (MEFI1 and VST). It went 75 when I started and 92 when I finished. I did a ton of research on here reading threads and whatnot.

I ended up reusing the MPI intakes, MEFI1 and the complete VST fuel systems I did the fuel rail mod and had injectors cleaned/ tested etc. I ported the intakes and plenums, used TPIS bored out throttle bodies as Smitty suggested, bored the engines to 509's, raised compression slightly to 9.1, ported the iron heads nothing major, did a full roller valvetrain conversion, custom cams with specs I found in another thread then sent the ECM's to Mark Boos for recalibration.

Tune through the mail is not the best as you will hear or frowned upon by most, but the last step I made was installing O2 bungs and an Innovate dual channel system so I could monitor and then have the ECM's touched up later. Sold the boat before having them touched up and never finished prop testing however I can tell you the readings were pretty darn close to where they needed to be.

I did not dyno the engines so I have no idea on HP but was very pleased with my overall outcome for the money spent. I'd go this route again in a heartbeat on that platform.

The best advice though is If you need to go faster buy a faster boat.

The runners were pretty thin to weld bungs to when I tried it, a long time ago.

https://www.boatid.com/comp-cams/xtreme-marine-camshaft-kit-mpn-k01-445-8.html?view=653568&gclid=Cj0KCQiAnNacBhDvARIsABnDa 6_ap9DYvcpJoCUodbJXeAkGy2DP9_LRbpkpV6EyBv92fj2lZXN NdUIaAkyVEALw_wcB

https://www.compcams.com/ez-efi-marine-self-tuning-engine-control-system-mercury-marine-base-kit.html

Ok since were talking intakes, EFI and air flow I spoke to Comp about a cam and they recommended the cam kit in the link. What do you guys think about this kit? I am on the fence about going to a dry tip and deleting my silent choice exhaust but not sure its a terrific idea as I am worried I will get constant complaints on my lake about noise.

Also I see F.A.S.T is coming out with an EFI system for mercury based systems.

Nice kit, should be dead around 4000 RPM

I had these for sale and no interest. Smoking deal since I had waaaayyyy more than that into them.
Now they getting modified shorter.

https://www.offshoreonly.com/forums/...tor-bungs.html

Doh ! Don’t know how that slipped from my mind. :banghead

What would you recommend for a good performance cam profile? I have seen a Crane 731 or 741 cam mentioned in other posts before.

I think you would be better off asking someone like Bullet Cams. I ran a flat tappet hydraulic 233 / 241 in a stock 454 mag, pulled real nice to 5400. Hydraulic roller would be much better on a 112 LSA

My block is a Gen 6 502 Roller, the valvetrain is roller and the block has a casting that says MK VI.

Then you would use a roller, I think you could make more power with something more modern than the 741 but I could be wrong.