I am not concerned with the lowend power gains an exhaust scavenging setup would give me, I had a b&b for years and sold it recently. I am willing to bet I will make more power with the exhaust I am making than I would have with the B&B.
AN x-pipe also deadens the exhaust tone a little And I would like to hear the true exhaust note.
also the way I am designing my exhaust makes an x pipe not really an option without defeating the purpose.