I have read numerous threads that Vol/Bols are set lean from the factory. I recently did some playing with stock mufflers (installed shorty glass packs into the empty muffler) and when taking them apart I noticed that there was an awful lot of black exhaust soot (not oil carbon-but gas carbon) in the mufflers. To me that says "rich" not "lean". My bike is stock (1300 miles) except for the mufflers. When changing from the stock mufflers to the glass packed ones I noticed a distinct puff (large one) of black smoke on start up and subsequent throttle increases. It went away after a minute or so (FI computer re-adjusted for the decreased back pressure?). I'm a fair mechanic (played with lots of carburetor vehicles) but I'm not to sure about FI (except for diesel engines). My question is; If it seems to run rich (black smoke) can I install a K&N air filter in the stock housing without having to re-map? Any thoughts would be appreciated.