The inlet sides are open - no filters other than a thin mesh

are the intercoolers clean,spider webs,,mouse nest,.......

I'd put a scanner on it and see if your tripping the knock sensors.

No

Internal exhaust flapper stuck partially closed somehow??

Not really familiar with prochargers. Is it normal for them to not make any boost until 4500 RPM??

I did check the intercoolers and they are clear of any instructions. Knock sensors is something I need to check

There are flappers in the tailpipes but they're just the rubber ones from CP Performance - I don't know how they could not be forced open. Something to look at though.

It is normal to start seeing boost around 4200 - I'm seeing around 2 psi on the other motor @ 4500. The Prochargers are based on rpm.

So over the weekend I swapped blowers and intercoolers and the problem has not changed. I put a smaller prop on the side that I'm having an issue with and was able to run the rpm up to 4800 but again saw no boost. At that rpm I should be seeing close to 5 psi and running that smaller prop with ANY boost I'd have hit the rev limiter easily. I think I've ruled out pretty much everything. I'm leaning towards an intake leak but how would that go bad from the dyno to install?

There’s no way that the tensioner is acting goofy and the belt is slipping is there? When I had m3SC’s in my BT I had to tighten the port blower belt to what seemed like overkill to get it to match the stbd engines boost. Sepentine Belts, not cog belts. I think you’ve ruled out about everything else.

i put new serpentine belts on both sides over the weekend and tightened them up to the point I was afraid to go any tighter and no change. Hooked a computer up and it shows zero boost @ 4000 rpm.

Where is it picking up the boost pressure at ?