Fitted one of these few weeks ago. Mark at Neptune a pleasure to deal with. Polished textured stainless oval muffler. Gorgeous sound (compared to stock of course!)... Stupidly loud with baffle out and also noticed slight power reduction at bottom end. With the baffle in performs better than stock (minor of course) Getting slight backfires if changing from 1st gear at 40km/hr 8000rpm... Is that a concern? I really don't know/understand about lean running etc. Had it serviced and apparently it didn't need re-jetting. (it's injected, not carb) Ran low on fuel, filled up then few days after filling up was getting intermittent flat spot in either 1st or 2nd. What do I assume?... Bad fuel? Or exhaust related? Was running sweet for the few weeks before most recent fuel fillup.