One of those aluminum magnum heads has an exhaust port that is usually too tall or low (forgot which) for off the shelf headers. MP really screwed the pooch on that one. I think it's the Magnum Commando (or Super Commando) heads.
Both heads require work from there OOTB condition to get what your looking for. Do yourself a favor and contact OU812 for additional info on which head would suite your purposes best as well bang for the buck.