Single pane vs Dual pane

The single plane intake will make the most power at higher rpm. But you have to consider the combo as many times on a street car the dual plane is the way to go. In most cases the single plane needs the gear and convertor to make it shine. My sons 400 in his Dart uses a Performer RPM dual plane and has run 11.55 @ 116. With a single plane it ran 11.59 @ 117. It had more mph but was not as strong on the low end and mid range. If he had more gear and convertor the single plane would win. He uses 3.91's and a Dynamic 9.5 convertor.
As for 400 hp out of a 383.......piece of cake. We used to have a mild 383 in my boys Dart that was basically a stock 383 with the MP .484 cam , headers , Performer RPM and 750 DP. It had a TA 10" convertor and ran 12.31 @ 110 in his stock body Dart. When I put the weight and mph in the calculator it came out right about 400 hp at the flywheel. Ron