Went from a 26pitch 4blade at 67.8gps to a 30pitch 4blade bravo at77.8gps 5000rpms wish i could spin a 28 harder but cant change the rev limiter nobody works the 555ecm yet and i dont want to hit the rev limitor cause mercuiser shuts injector pulse down instead of ign down.

FMI, send your PCM555 to Whipple! They can reprogram your computer.

fmi is that a 496 mag or 496 ho ? great results ! plan on pro charging my 1998 26 sonic with 502 efi next year!

ILL try talking to whipple but arizona speed and marine and a place in california both places said no one reworks that ecm 496mag..

Whipple DOES reprogram the 496 PCM. http://www.whipplesuperchargers.com/...sp?ProdID=1190

Hey tried whipple they say they only do there own system so they wont help either i guess im out of luck for now..

A 271 fastech running 67.8 on gps with 375 hp?
I saw a test on one it ran 63, the fountain was 5mph
faster, that would make it run 72 with an ho.
The formula has a lot more room but I opted for the
5 mph. Either I'm bummed or you have a freak.
Powerboat has one with a 500 I'll have to check
what it ran, seems like 70. My HO runs 67, Enjoy John

Hey my 271 ran 62 on the gps when i first got it but i took the plastic baffles out of the exhust and had a prop worked then i saw 67.8 nothing crazy just did a little work.

I had the stage 2 program done from Whipple and I am running a Procharger with a 5psi kit with no trouble and now have a 5450 rpm limit.

Did you ever run the boat with the Stage 2 kit before the Procharger. I'm interested in seeing if it helped at all.