318 build #2 "cost minded" for the '74 Duster

273 said
There is another dyno test between manifolds and found that best combo was one 340 and one 5.9l forget which ones but here's non magnum manifold and header shoot out

Installing Exhaust Headers Into 300hp Crate Engine - Mopar Muscle Magazine

rumblefish360 said
Oh yes! Thanks remember. Well, on THAT particular combo, the 360/300, the call of exhaust is for the owner. 311 or 327 hp, 403 or 425 ft lbs of tq.
That’s 16 hp & 22 fr lbs of tq to decide on between exhaust manifolds and tti headers. Which will make more power once you out there exhaust system on. They stated no collector extentions on the headers. All on a stock engine.

No Magnum manifolds tested. So I’d still like to see what that deal is worth. Anybody?

The factory writings stated the best exhaust manifold combo was the drivers 340 & Magnums passengers side. I still see it loosing to headers. But the owner/operator & spender of money will have to decide if it is worth it.

1971 CY Dodge Dart said
Headers didn't seem to make much of a difference on this combo over manifolds.

I think that manifold/header test is flawed. I base it on the fact that Holdener on YT tested a 300hp Crate Motor with the dual plane M1 intake against a JY 5.9 with a beer barrel intake and got virtually the same numbers. If dropping that extreme runner length intake won't pick up power, I don't think much will.

My opinion is that the real restriction on that motor is the cam, and until a better cam is swapped in the real advantage to the manifolds and/or headers isn't going to show itself. Not saying there weren't advantages shown, just that it was less than what it would have been if the exhaust had been the restriction.