Mick, personally I put in a older Yoshimura one with pretty much same setup in the 915 Cobra Girl last time with a big NOS OEM bottom roller. My two big metal ones had a little spot in each one I didn't like and these weren't available then. I like what I'm seeing, know kmb69 and Mike Rieck all like what they're seeing so far, turbo engine will go back with one. Three going in the RC Triple, K, Bill