8mm bolt sounds like the cap on a standard tensioner. Those exhausts have been well done. Shame we have to have number plate. I'm sure there a way of tidying that up. Diffrent tail tidy and end caps The links look a bit close to swingarm. Does it not catch the links on compression around the weld area. Looks to be a bit of a sharp angle.
I believe I have OEM tensioners. Have ordered a couple of billet ones from ebay. £56 all up & they look well made. Will probably add a positive locking device to them to be sure.
Thanks for the compliment on the pipes, VTRDark. They clear everything apart from slight contact with the tyre when two-up & bumpy. That's why I've got what appear to be chicken strips on the right hand side. Honest!