I've been running a SuperTrapp for about 3 years now and have been impressed with the performance improvement. I have rejetted the carb and installed a K&N air filter. This thing now has booming acceleration up to 60 mph.
I have never been able to get rid of the backfires. The backfires now occur at gear changes 1st to 2nd, and 2nd to 3rd. There is a ka-pop sound that occurs frequently. I does sound agressive, not like the ka-boom at slow speed with the stock muffler.
Question: Is there a way to dial out these backfires?
I run the mixture screw at 1.5 turns out.
By the way, the SuperTrapp weighs 10 pounds less than the stock muffler, so it is easy to justify adding a windscreen and and a set of Willie & Max bags without much weight change.