I have a 2003 38 t/s cigarette with 575sc's. when I bought boat i was running 33 lab finished 4 blades and running 90-91mpg. After investing in intercoolers, the boat would barely get on plan with the 4 blades (washing out due to increase in hp).I then tried 32 4 blade bravo's 32's which didn't help the problem and after further discussion with Bob Teague i spent 3k more and purchased 28p 5 blade 15 1/4 maximus. Well, the boat comes out of the hole like it did when i purchased (great) but now im running in the mid 80's and bouncing off the rev limiter which was increased to 5600. Any input would be greatly appreciated. I spent what i thought was good money on a smart investment to help performance, increase reliability and prevent detonation and know i've lost approx 5 mph. Should i be changing to a larger 5 blade??? thanks for any help you can give!!

The pitch of the Maximus props is too small. I am not sure why you were put in 28 pitch props unless the gear ratio was changed to 1.36 when the intercoolers were installed.

If you have 1.5 gears 30 or 31 pitch 5 blades should put you where you need to be. The 28 pitch props are just too small to get the speed, the boat has the potential to run, at the rpm range of the motor.

Agreed, stick to the 15.25" diameter Max and go to the 30 or 32 pitch casting. Testing with the box stock versions will tell you which casting to work with.

Sorry you were let to 28's. Some one dropped the ball there.

so what did ya end up with?

Man those 5 blades are going to put a huge stress factor on the drives. Be careful.

I went from a 4 blade to a 5 blade, it should be 2 " 's of pitch. It was for us anyways.
I went from a 28 b1 4 blade to a 5 blade 26" . Man that prop has a TON of bite