More exh with more cubic inches, 1.600" exh valve. Yes true, but there is also more pressure in the cyl to 'push out' the exh gas.
Cams for turbo engines often have less exh duration, yet make more HP than a NA engine, so more exh gas to be removed.
NA you will kill power and RPM and not adding exhaust duration. Already proved that more than once.
And I'm not talking abut 4 degrees like Comp loves. I'm talking 12-15 degrees more exhaust timing. Making the engine pump out remaining exhaust gases is a sure fire way to kill RPM and lose power. Pumping losses are real.
