yeah the guy from jackson racing said they all have different sizes? i dont know what the hell this guy was talking about. so he sent me a 3 in pulley that i think will blow the motor up? i see everyone else using a 3.4 in pulley at 7-8 psi i cant imagine how much more that will put out in my car? he said the crankshafts are different and would make a difference in boost? not only that but the part is not returnable how bad does thst suck ass