I am sure this question has been beatin to death on is board, however I am new at this marine stuff and just purchased a 35 lightening with 2004 stock merc 502 EFI. Is there any simple upgrades available to boost HP. I have been told be careful because some of the internal compnents may not be able to handle any extra power. They are suppose to be 415 HP from factory. Any info would be great.

Thanks

Aluminum Heads Larger Cam New Exhaust.

Headers are a great place to start.........mild cam etc.......

Something like a set of headers from Stainless marine ?

call mark at precision marine 504 469 7463 he is the top efi man and can tell you in very short time what would be your best and safest mods.

Thank you , I will call Mark today.

If I'm not mistaken, wasn't the Merc 502 discontinued when the 496 was introduced in 2001?

The best "boost" is BOOST! Add some HP manifolds, and slap on a couple of Whipples, and you got yurself one fast boat!

In my opinion, the vortech is the best system on the 502MPI. You will have 700HP and depending on how you run it, you will still have reliability. If you go the extra mile and beef up the valve train, you will really have something.

Also, Any mods you do will have to work in conjunction with the computer for that engine. Tyler Crocket has an excellent up-grade package for the Merc 502MPI that includes surfacing the heads, larger stainless valves, valve job, roller rocker arm conversion, hydraulic roller cam upgrade, CMI headers and computer mods---good for about 100hp per engine........or you can go with a Vortec supercharger kit or something comparable. Either way it will cost THOU$AND$.