i was looking at the aftermarket heads on m/t tonight (the patriot heads), and am amazed by how expensive they are. im wondering if it would be possible to take stock pi heads and have them machined to be like the aftermarket ones? i have no idea what acctually makes the aftermarket ones better (more flow of course), but how do they accomplish that? could a good shop turn stock heads into good aftermarket ones that would make some nice numbers? if so, how much would that cost?