OTO looks like it is 3 inches, CTC looks around 2 1/2(ish). Here are a few pics if it would help any. These pictures are of the exhaust hanger that I used on my 2005 GSXR 600. It mounted perfectly to the mounts for the pass. pegs. I have no idea where Columbiana is, but if you happened to be in Columbus, you are more than welcome to see if this exhaust hanger mounts up to your bike. And while you are here, I would like to see if my CRG brake lever fits your brake lever. According to CRG it should.