which kit the "max flow efi kit or the super magnum kit for efi engines would be the best choice?

I believe those two are the same, just a different name on filter.

BTW, I put a kit on my '00 502mag. (flame arrestor, ECU, exhaust, labbed prop)
No big deal! The flame arrestor make the biggest difference. 2nd biggest difference was the recalabrated computer. ONLY because the rev limiter was raised higher, NO performance gains.

If I were to do ANYTHING on my new boat, It would only be a flame arrestor. (maybe a labbed prop)

Hey BillR,
I can't believe you saw zero, zilch,notta one MPH gain after installing all that stuff and lab finishing your propeller. How heavy is the boat and what make and model? Sounds like the boat is very inaffeciant.

billr give us some detail, boat , what kit,
exhaust etc. everyone i have talked to saw gains of 3+ mph.

Go for the blower!!!!

Something else is holding him back. With all that stuff he should have gained at least 400 to 500 rpm. Lab finished prop alone should have got him about 300 rpm. Good exhaust is good for about 200. He has a problem ! Possible a fuel flow or ign. curve problem.

stevew do you have any experience with these
upgrades or know of any body else that does,any info would be appreciated.

I also insalled the Vortec kit on 502 Mag in a Formula 242Ls. I saw very little increase. I think the biggest benefit ws from the MSD ignition box in the form of a cleaner transom and what seemed to be a stronger idle. I then added a decent exuast and saw an increase but not with the kit. If you are gonna spend money, do it on some good manifolds and risers if you have not already done so.....just my opinion

[ 01-16-2002: Message edited by: Celtic Banshee ]

I guess I wasn't clear.

Yeah the labbed prop DID help on speed.

But the ECU and the exhaust gave 0 on top end.
The flame arrestor helped on hole shot and midrange punch.
Stainless marine exhaust also helped holeshot and midrange, but not gain in top speed.
ECU helped by allowing the motor to rev to 5100 rpm. But felt no performance gains except the rev limiter would not be holding the labbed prop back.

Boat was a PowerQuest 280 Silencer w/ a 502 Mag

Isn't the rev limit set to 5100 from mercruiser? Mine is.... (1999 502 Mag with Gil wet Offshore exhaust and a K&N Air filter, had the prop tweaked from a 26p Bravo 4 blade to a 25p, balanced, blueprinted) Also installed AC Delco Rapidfire plugs. Midrange punch is very noticable and top end 1-2 mph.