IMHO, before the dabate about whether it would make 500 hp gets too far along, there are a couple of things to consider. Its easy to say a bbc with a roots blower won't make a lot of power, and although I agree that a lot of blown street cars are doggy, a well setup blower motor can make a ton of power. I'd want to hear from the owner about what has been done to the engine. After all 454 is just a start for a big block. (you can get that much out of an aftermarket small block fer crissake!) GMC blowers come in lots of sizes.(I think a blower off a 3-53 detroit engine would be neat on the vg-30 that is sitting in my garage.) The blower off an 8-92 would be just what the doctor ordered for a built big block. Not only is the size of the blower important, but the pulley that drives it makes a difference, when one of those gets overdriven, the boost goes up FAST. A for at he blower sticking up too high, I have a suspision that this thing wasn't built to be a sleeper. (I could be wrong of course;) )