I bought a set of Edelbrock RPM performer heads for my 512 build a few weeks ago. When I opened the box I was initially impressed with the quality. Sitting next to the 452's that came off the motor, right off the bat you could easily see that they were going to breathe better. I took the advice of folks like Rusty Rad Rod and others to get them cleaned up. I took them to a local race shop where they cleaned up the bowls, did some porting and worked the valves. I seen the heads yesterday (which they're wrapping up on) and i'm just stunned how much was cleaned up and opened up. What I thought was great when first receiving the heads, now seamed like some rough looking cast with some slop and far too much excessive material.
I agree with ruster on the headers...Being you're not going with a stock look/motor, why sell yourself short by loading your engine up from constricting exhaust manifolds. You're already making an attempt to make your engine breathe better, why choke it? I just picked up a set of Dougs and there really is no comparison between them and the boat anchor manifolds.
I'm no pro when it comes to building HI-PO modified engines, mainly use to stock/mild rebuilds, but the folks here, including rusty have really given me a hand putting the right pieces in place to build an engine to how i'm gonna be driving the car. IMO, If you're spending the money, don't sell yourself/motor short by just buying a convenient package. Again, just my opinion. Good luck to you either way.
BTW Rusty...Talked with the boys today in Bowling Green at QuickFuel, Q-Series 950 is on it's way..Thanks again.