From what i read, at some velocity flow increase stalls. With a ported 906 on a 535 i would think that will happen somewhere around 6000 rpm? I also read that higher rpm creates more energy for filling the cylinders, so at some point that would come into play. Less rpm equals less increase from exhaust and intake tuning.
From what I understand, the RPM at which inertia and wave tuning start really taking effect is about 6,000. Under that RPM, not much effect, the higher above that RPM, the more sensitive the engine combo becomes.
I have little experience with low RPM combos, though. Every high RPM combo I've built has responded to more displacement, even when the cylinder heads where the choke.
