If you went with the XE256H cam, you could go with either manifold. If you went with the XE262H, I would most certainly go with the RPM manifold. The motor I put this cam in is a 9.25:1 compression 350 with Vortec heads. If you're feeling rich, you could just buy both manifolds and try them both out. Also, match it up to a set of small diameter long tube headers. 1 5/8ths in primaries and a 2 1/2 inch collecter.