I did beef up the bottom end, but it lasted 5 years as stock efi500 and 5-6psi before I did. My ECU is custom via the boat and an air fuel meter, the only way I would suggest.

I see just a touch under 90 with a 540 and 7psi, 28' Nordic, 1.36 gears at 5500 and a 28P bravo.

My buddy and I have same boat, he has whipple, I have vortech. There is so much mis-information out there it's crazy. We both come into boost just around 4000 rpm.

If you have a vortech, you don't need to "wait for rpm" to get the boost to "kick in". Just like the Whipple isn't making full boost all the time.

If we we both cobbed the power at 3000 rpm, totally in vacuum, we would both get to the other end of the lake about the same time.

There is no waiting with either one, the power comes on, RIGHT NOW.

This is rarely getting over 4000 rpm on this video. Plenty of power on tap. 540/7psi, 28' Vortech

http://www.youtube.com/watch?v=PhHfwyKf5E4

i have a 38 scarab avs with m4's on 540's and have had nothing but problems with the drives. motors have been great make alot of power, but i keep blowin up drives. imco sc's cant hold the power on this heavy boat. upgrading to SCX with sc lowers. only issue i am having is its running way and i mean way to rich. running 850 quick fuel blow thru carbs and they just arent rite. going to 750 pro system blo thru carbs. whats everybodys thoughts on going back to 1.5 ratio on new drives. guy with a 42 fountain with same motors says it helped his motors a ton with putting all the load back on the drives instead of the motors. he is running 13-15lbs. of boost i am going to stay with 5lbs.boat is fast enough. 107 is fine with me, just want more reliability with the whole package. any feedback would be appreciated! thanks

Save yourself the headache, spend the extra $ and buy Whipples.
They dont rattle, they are WAY more efficient, the intercooler isnt a box on the floor..etc.Not saying Prochargers can't make a lot of power, but its doing it the hard way.
Thats going to be my only post because I know the posts that will follow. If you want more info PM me.

I love my prochargers. Zero issues after 220hrs 7psi. Talk to someone like ben at precision power offshore. An EFI might be the answer. I have drive issues also but any high hp boat will. You should consider the complete imco scx for full strength. Arneson bravo conversion is n ice also and overall the best bang for the buck.

arneson are twice as much as SCX's. i already have the lowers so the best price i have had is 10,300 per side. Thats the SCX upper, new helmet,coupler to bolt the lowers onto the uppers and the larger drive reservoir because they hold so much more drive fluid. arneson bravo conversion was 23500 a side and thats not installation or props. arneson would be well over 50,000. SCX will be half that. i also love my prochargers i cannot justify spending all that money on whipple's when i already have this system. so, looks like im buying imco SCX! get the fueling issue delt with and i will be back in action in the spring how often do you need to change the impellar in the procharger blower??? i have been told every 2 seasons.. i LOVE the way these big m4 sounds!!!!