Typical Aprapovic ...not much louder, mostly changes the tone. I actually went with the Tyga full race exhaust and it is too loud. Kind of obnoxious but I am primarialy using the 390 as a track bike so it is not really an issue.
New Akrapovic Carbon Slip on for sale. Purchased new , rode 100 miles with it and ended up buying the Tyga full race. Paid $650 new , will accept $350+shipping. Located in Foster, RI USA.