What are you going on about? Edelbrock Performers are fantastic heads. They're great on a 302. They aren't great on a 363. Don't make it out like I'm bashing Edelbrock. That's nonsense.
I've seen the Cobra intake make close to 400rwhp on a stroker. With a turbo or blower, that car is going 9s on pump gas, no sweat. I guess by your standard, the Cobra owner should never have bothered upgrading to the RPM II. I think the RPM II is a fine intake, but as I said, "I'm not sure" it's the best idea on this displacement. I'd need to study it a little more. In fact, I must add that while it's not the highest priority on my list, I might just design a little intake show-down on my setup. My first performance shop talked me into the TFS-R-Box, but I think I'd have gone with a ported HSII. Otherwise, I like the RPMII as an alternative. I'm working with less displacement and a very mild cam, though. The more aggressive the cam and lower the rpm and displacement, the less flow you need from the heads and intake. The more mild the cam, like mine, the more flow you need. So, we'll see how it shakes out, but I think I'd benefit from either of the other intakes.
You suggest that the Scat internals must be forged. Cool assumption and all, but then don't you wonder why someone who just spent thousands more on a short block to increase its power potential decided to save a few hundred on the heads, almost no savings on the headers, and restrict the potential unnecessarily? Doesn't it concern you at all when the owner's evidence is, "well the guy I bought it from said so."?
Go ahead and show the article/link the video comparing the 1 5/8" headers with the others. Your "IIRC" comment lacks any details that provide actual insight. If this was a from scratch build, would you put those headers on a 363 with a "

it, good enough" mentality you seem to be chuckling at me for not having when I'm the guy actually making the offer on a car?
You're right about the 2.5" exhaust. That's what I run on my car without concern with intent to be at 900rwhp+. I was thinking it was stock size, for some reason, even as I typed 2.5.