68-70 Hi po manifolds vs quality headers

Mopar Muscle did a exhaust comparison on a mild 360 (300hp) crate engine.

Results on 340 Hi-Po man vs TTi's

340 man......4600 rpm......315 hp
TTi's...........4600 rpm......327 hp

340............3700 rpm.......409.1 fpt.
TTi's..........3700 rpm........425.5 fpt.

Not sure if this helps,but thought I would pass it along.