The heads on a Flowbench 600 run 392 CFM on the intake port at max lift, 270 on the exhaust which is just hilariously high. Average gains were about 30 - 40 RWHP on their Mainline Dyno with 91 octane. I was quoted $1425 to port, polish, clean, and verify flow on the heads. Reusing stock springs and valves. Now here's the issue I have: I feel like the heads alone are nice. But it needs to paired with cams too. If you're ripping apart the top end, might as well do the whole deal. The heads are so big and so well ported that there would be basically no loss of low end, mid range may slightly dip (like the Roadrunner vs the Gen 1 Coyote) but will continue to carry on, even with higher duration cams, which is what the Voodoo needs. It doesn't need more lift. The Voodoo is maxed out on lift as much as it can, 14mm. So I'm in a conundrum. I don't think I'll do it unless I have cams to go with it. While the heads may give 30 RWHP, that would be compounded with cams PLUS what the cams would provide stand alone as well. It's difficult to figure without a real baseline but with these ported heads, long tube headers, a dialed in tune, stock intake manifold, filter, snorkel, and MAF there was a 100 RWHP gain but only theory. Since the original project car was sold before the whole project was done, they didn't get track testing either unfortunately so that's hard to figure.
Slight recap with some theoretical conclusions, the car originally came in with an E85 Lund tune, long tubes, no cats, and stock everything else and it was putting down 505 RWHP on a Dynojet 224. In THEORY, the Mainline Dyno probably would have read around 470 RWHP in that configuration. After heads, a fuel switch to 91 octane, tuning, tuning, and tuning some more, they ended up with 525 RWHP on the Mainline Dyno. Theory would tell us about 550 RWHP on a Dynojet 224. Or about 630 flywheel. What's really important though is what kind of torque curve change I'm looking for. I don't want to lose any low end but I don't need to gain any either. Once the Voodoo takes off like a rocket ship @ 3500 RPM, it gradually dips down in torque and eventually ends up at about 320 RWTQ @ 8200 RPM. I want that to raise up and be flatter and hold that 375 or so RWTQ starting @ 4700 RPM. Instead of a dip down to 320 RWTQ, I'd like to see more like 350 RWTQ at redline which is just about 550 RWHP @ 8200 RPM. While the goal may be met, I still would feel weird about not having done cams as well.
So the homework continues for now and no decisions can be made as of yet.