I've just changed mine to an aftermarket one £16 off Ali express it has a removable baffle but it made very little difference with it in or out, out was obviously way too loud I had to re set the throttle position sensor to max to get it to run without a flat spot, I wrapped the baffle with 1mtr of stainless steel exhaust wire wool that did the trick it's still louder than the very quiet standard muffler but nice tone on the over run no back firing I also fitted a 19 tooth front sprocket so I only need 5th now over 60mph so cruising speeds much better