Coming from a guy who is using onroad manifolds on off-road engines - I can tell you that a super long off-road manifold on an engine with higher timing will make the engine run hot and fall flat on top. A shorter manifold made the engine happier all around. I basically have an off-road engine with onroad timing using an off-road pipe and onroad header in the most unlikely of places - and it works significantly better than the super long off-road header and 053 type pipe get could. The short exhaust gave a 14% increase in top speed. I think that says something about how the pipe changes the powerband and that it can and will boost power if the timings are correct for it.

Let’s derail things a bit - pipe to port or port to pipe?