When we talk numbers here, nearly all of the numbers in the past have been on Dynojet dyno's. With the large number of other dyno's around these days, dyno numbers are going down. That doesn't mean the car isn't making the performance it was before, it's just the stick used to measure it has moved. I'm still working off the old measuring stick.
My stock 90 made around 212rwhp on the dyno at last years shootout using a stock blower and 10% overdrive jackshaft pulley. (hmm, maybe 5%, I forget) It was making 11psi during the run and is an auto with stock converter. That dyno wasn't making many people feel good. (Note a trip down the track in 14.667 at 93.89 at 4200lbs puts me at around 263hp which I believe is a crank number)
Get the MPX pushing out 20 psi, with less hp stolen than the stock M90 making 11psi, and I see close to 300rwhp very possible.