I've seen A LOT of posts about making HP with a 318-So why is it so ???

“If”, and that’s really a big big if...... I were to build a mildly hotted up 318, I’d have to do it a little differently than the stuff I’ve done before...... just to change it up a little.
Since the EQ heads are gone, I’d like to see just how F’d those SM Magnum heads actually are....... so that’s what I’d use.
KB flat tops, a mild cam that would work with a stock magnum valvetrain.
I’d probably use that SM universal intake, avs2 650 carb, etc.

I know Jesse has used a version of that head and wasn’t too happy with them, and even though the flow was way less than an EQ head, they were a fair amount better than 675 or 302 heads.
Edit- I see Promaxx shows a replacement magnum bare head for $272/ea..... so I’d probably give those a shot.