friend of mine works @ Pro charger here in KC, have you called them ?

Definately is a dam interesting one thats for sure! I also cant wait to hear what ya find! Another thing you could try is dropping the pulley size down one, this will bring your boost in at a lower RPM, I downsized mine by 1 size recently because it wasnt building full boost at WOT. I know your having a different problem but would be interesting to see what procharger says about it.

i have. Spoke with two different guys there and they're baffled too. Had me check the obvious, belts, keyways, etc. but no other suggestions unfortunately.

Ive not read this complete thread but could it be a timing issue, are your ecm's locked or can you get into them and look at the timing and fuel tables ? have you verified 8* of timing in base timing mode and full advance ?

on the bottom of the hull,,is there anything in the water path to the motors prop that spins up?are there drive showers?is the trim indicator true to the drives position?

This is a long shot, but was anything done to boat that would restrict air coming into engine compartment? Reason I ask is on mine I found a couple of the bilge air inlets taped over inside the bilge when I removed the vents for waxing. Maybe try cracking open hatch an inch or so while running?

These are 540's with M1 Prochargers? I'm shocked that they make any boost.
Out of curiosity, what did they dyno?
I can't wait to hear the fix.
I leak tested an engine a bit ago and it leaked down good. When the heads were removed it was missing part of the pistons I believe on the exhaust side. Engine was down a little on power, but nothing that would have said tops of pistons melted.

L was going to say to check the air inlet , do you have an exhaust leak in the engine compartment that is polluting the intake air?

ECM's are not locked and we did go over timing and ran O2 sensors in headers. Everything looked good

I thought about that too but nothing was some to the air inlets a Dale I've even tried running with the hatch open 12 inches or so