That manifold is happy from about 4000-up. On a big stroker, it could work at 3000 with the right cam. In most streetable apps, the Performer RPM is still the way to go. Most engines spend most of their time in a range where that intake isn't awake yet. If you are going to operate at 4000-up, it is a good choice. I did considerable work to it in the plenum, but the material is there, and it wouldn't be bad out of the box.