Usable power for the street?
The MP crate 360/300 is 55hp better than stock.
I think that 55hp increase is a smokescreen because it's without accessories, an air cleaner and with headers. That's the only way he got a 300hp crate motor to make 300 hp. And don't forget that a JY 5.9 with the same setup but with the beer barrel intake and EFI made within 1 hp of the crate motor.
So the 55 hp "increase" is because one is engine dyno numbers and the other is as installed in a truck.
Something else of interest, that same motor made 291 hp with the small outlet Magnum exhaust manifolds, 294 with the large outlet manifolds and 301 with headers. Only 10 hp for headers compared to stock, and only 7 hp compared to the early manifolds? Pretty small return for what it would cost to put good headers in an A-Body.
Just seems to me that while a stock 5.9 with a carb and headers is a decent option, don't expect much beyond 300 hp unless you put a cam in it first.
