Thanks Stace.....

Just plugged some figures into Guiseppe's calculator...

320bhp (240 KW) at 90% IDC = 560 cc/min, and that would only be at the crank.....

400bhp (300 KW) at the crank is about 240 KW at the wheels so yes its a GD manifold with the 816cc decaps.

Good discussion....