Have 98 32 Fountain stock 502/415 EFI's 100 hrs.want to increase power with no blower, is there a cam and lifter swap, is the bottom end and pistons same on 415 and the 500's. can I still use stock exhaust and EFI ect. and help would be appreciated.

thanks jmph

that is a good question, i'm sure some people can give you some good answers though, I do know that if you swap your cam shaft for a bigger profile it would be a good idea to add some aftermarket exhaust so you will cut out the water ingestion problem with a high overlap cam, a lot of the small upgrades will not give you much at all[like flame arrestor, MSD ignition, ECM remap ] if you do change cam's you will need to get the ECM remapped , a good place to start is tyler crocket marine, he has upgrade kits and can remap your ecm also,
www.crockettmarineengines.com

I have a couple of friends that just change the exhaust; Little if any gain...

My plans are to change the cam, have the heads ported, change exhaust, and have the ECU remapped.

I don't believe that the bottom end is exactly the same as the 500 but it does have the good stuff. No problem adding more kick...

Call inovation marine in sarasota fl, they told me what to do to mine, but i forgot since i sold the boat with the 502 efis.

I talked with Tyler Crockett this week about the very same thing. He said he was getting between 500-510 hp out of the stock 502 with exhaust change, and all the things he does. He quoted me $2,400+- for the parts, and said installation would be somewhere around $1,200-1,500. So for less than $4,000 you could pick up about 100 hp.