I can’t speak much to hp numbers, I feel like a lot of people in the community shoot for 300 neighborhood at the crank without intercooling. I never had mine dynoed so I can’t say for sure.
As for twin charging, though.... the consensus for a long time has been that the m90 would be a restriction to the turbo, since the cfm of the turbo is probably pretty far above the blower’s cfm.
Basically leaving the supercharger intact is creating a choke point for the turbo trying to push air. Sure maybe it sounds cool to say to someone who doesn’t know what you’re saying, but you’ll do better power going just turbo.
