If you took the performer 318/360 and opened the runners to ld/rpm/ag sizing, it's a dead heat on peak HP in most every case. The Ld4b with those 318 ports runs right with an ld/rpm/ag.
There isn't much difference in any of those intakes for peak HP when the openings are the same. If you have an LD340, it's a waste of time and money to get an AG intake. Block the heat riser and run the LD340
The performer 318/360 is supposed to be the low rpm intake making better tq according to some, yet the LD/RPM/AG all made better tq throughout the range on those 425ish HP 360. Some of the difference may have been differences in carbs when tested.
Intake air flow and port sizing isn't that important on most of these engines. There are many cases where an intake flowed more air than a different intake on the same head. The one that flowed LESS air kicked the snot out of the big air mover. It's the combo. Look at the super victor, without serious work, it's a dog of an intake yet flows a lot of air.
Another is the mismatch of putting a 340-360 sized intake on 318 heads... it's not that big of a deal and way overblown as a giant taboo.
