I think that's a Pit Crew Racing exhaust but it's weird because I see what appears to be another tail pipe sticking out past the right side of the rear diffuser. PCR made several different styles of twin canister exhaust systems. If it's not PCR then it's one made by an obscure Roadster tuner who is no longer in the market place. Back in my early Road&Ster and HyperRev magazines I've seen a couple of different exhausts that were all like the PCR Clubman but I can't recall they're names right now. I've recently moved and my Roadster resources are all boxed up in the attic.