I thought less backpressure, but now I'm going to leave it in. I don't want to add anything to our already polluted air. I am going to call Dinan this morning (he's only a few miles from where I work) to see what they recomend. If you want more power start w/the header.Why not a cat? It's time to replace an 18 year old exhaust system on the 633. Anyone have suggestions for a replacement? I don't want it loud, the stock system is load enough, I would like some more power and I'd like to put it in myself if possible. I'm going from the header back. If I could get away with it I'd not put a cat on it.