I recommend all of them, I'm just going to use the ford rr's. The trick flows were the most accurate in tolerance that the guy could find. But like I said, his was "race only" and had to to spec'd exactly. On a daily driver/occasional strip car, I don't think that kind of accuracy is necessary. The nmra people are looking for cheaters, so they have to maintain tight specs.
As far as aluminum rr's go, I would guess that the head/cam manufacturers want the best numbers for their products, and the full rr's are lighter and faster than steel, less rolling resistance. That's why they're big, fat suckers that won't fit under your covers without removing the baffle. They are lighter, but if built to the same specs as steel they wouldn't last 10 minutes before breaking. Hope that helps you out.
