I have a Formula 312 Fastech w/ twin 454 mag MPI's I'm only running 67mph at 5150, hitting rev limt with 28p bravo-1.. 1.65 gears that puts me at about 20% slip... That sucks. Hydromotive wants me to use a 5 blade and go down to a 27p. But I have read some say their boat got loose on them.. Anyone have a good set up.. Do I just try 30p Bravo-1's or will I stillhave the same slppage..
I guess I need to have the ECM reprogramed too to et more out of her.

stock motors? if so mercury or formula will tell you exactly what to run on there...

What is your goal ? If its ultimate top speed, then you do not want to go up in blade count. Stay with a 3 or 4 blade, with 3 blade being the most efficient. With that much slippage I would say that your current props need reconditioning, or someting is out of whack with the props. If your goal is better accelleration from a stop and midrange, then a 4 or even 5 might help.

I want more top end. The hole shot seems pretty good..I would think the slippage should be about 10% not 20.
Obvoiusly if I can't get past the rev limiter there is a good chance I'm under proped. I did talk to Formula and the following year they used 30's on the the same boat and motors. But If I'm going to drop $$ I want to iliminate the slip too.