I noticed that it's really only loudish when accelerating, when I'm at a constant speed, it's pretty quiet. If you think it's too loud, definitely get the core and spark arrestor. The arrestor creates some back pressure too, so if you don't plan on rejetting the bike, it will help. I must say that having my bike rejetted made a huge difference in how much better it runs than stock.
__________________________________________________
It's not worth doing if you aren't completely stressed out about it.
|