Is there anyone out there who can explain to me the theories behind intake manifolds? Specifically, I am asking about the hp/torque gains to be found in a larger/smaller plenumn, or longer/shorter - larger/smaller diameter runners. The engine I am using is the d16a6. I am looking to get a broad powerband from 4500-5000 and up rpm. Would I be able to find a performance gain using a d16a1 manifold or one from skunk or venom? Any insight would be helpful.

 

The larger are to allow more air flow of course. Shorter runners for higher RPM power.

The Venoms are extreme and would only recommend for LARGE turbo applications only.