I bolted on, a muffler, the bike is a CA emissions bike. It is so lean, factory, that at 3500, through 6500, it surges enough for me to call it a rocking-horse.
I don't know, I'm not the carb guy, but I learned that a free flow exhaust, and restricted intake, would create a richer than stock situation. By the fact that the manifold vacuum was raised.
This bike ran lean as ****, I put a muffler on it, and it seems to run a little bit fatter.
it's still lean as ****, I just don't want to burn a hole in my piston.

 

As long as your airbox is stock your probably not too lean as if you read your directions it said no jetting necessary and they are the experts. That dosen't mean that you won't benifit from proper jetting and if you change the intake side at all you will need to jet. There is a ground issue that causes the surging like you have there, hopefully someone will chime in with the fix as I never had that issue with my bike.

 

Thanks for the input, I know that re-jetting would give me better performance, but, it's a commuter bike.
I like the mileage I'm getting now, I lost 5mpg, with this muffler, but now I see eyes in the rear view mirrors.
I'm lane splitting through Hollywood, all day everyday. The extra noise helps!!!