From what i had seen for a street single the Schwitzer s300 style seems to work out best . But the confusion in on who's version will work best ? the bd seemed to be the most cost effective being that if you needed a down pipe its included but that was only offered with a 14 exh. outlet . HTT offers their htt2 with either a 14 or 12 housing and claimed that it will support more hp. & flow more air. I'm leaning towards the htt because i'm after better spool and i can get a 12 ext out let . also bd said that they can upgrade theirs to twins. I cant see why the same shouldn't apply to ht's . plus i head rumor that HTT is coming out with twins. MIKE