Found this over on riderforums user fencingdud101 posted about an arrow exhaust system he’d bought...
It weights in at 9.5 pounds, so it shaves just about 9 pounds off from the stock exhaust, and should make a good bit more horesepower after tuning, of course. We have a little fab work to do to make it fit the 2014 bike since it was made for the 05-11 models (Mostly regarding enlarging the header ends from 35mm OD to 41mm), so that will occupy my time for the next little bit, on top of making a custom seat frame and welding in some steering stops. Luckily we have half a year to do all this stuff!
So if you want to fit an 05-11 exhaust on a 12- bike you need to open up the headers OR use 35mm OD 1.5mm thick tube to make up some collars as i alluded to earlier.
Hope this helps ?