Speaking from relative ignorance (I don't know that much about the SL55 intake), I can't imagine why anyone would go that route. The SL55 intake appears (at least to me) to have a major choke point where it enters the manifold. I can't image that you would get much improvement over stock. Anyone have numbers handy on it? (Not that it matters much to me, my NeedWings CAI is on its way to me already)