Through last year I was using an Edelbrock Torker II. I picked that based on more 10 + year old manifold testing program from a magazine (Mopar Action?) I was running out of the box Performer RPM heads and 1 3/4" Doug Headers (D451). Guys who's engine and racing experience I respected were telling me I needed to get rid of the Torker and get a Performer RPM dual plane.
So, this year, I went to the Performer RPM dual plane, Doug 2" headers (D452) and had the heads ported.
The firm who did the porting, G&K engines, compared the flow of the two intakes and says there was a definite advantage to dual plane unit.
Performance wise, those three changes only picked up 4 tenths and 3 mph. Last year's combo engine dynoed at 502 HP. Didn't dyno this year.
Akron Don Gallimore