Phil,
Have you heard the Predators on a Speedy or America. That Bonneville reminded me of the Dunstall pipes I used to install on my old parallel twins. They even sounded great on my '74 Yamaha TX650A. The Dunstall replicas are available on ebay for $150 with shipping. I'd rather just get the Predators and not take a chance on the imitation pipes. The Predators have 5 discs that you use to tune the sound. Just wondering.
Janet's gonna love that sound, once you get them put on her "other husband". Raynea calls my bike, "Your other wife".