TC,
Could you elaborate more on this topic? If the bike runs leaner....what would the "symptoms" be to look out for?
G
One would be really high oil temps; excessive heat coming off the rear cylinder (which is already damn hot). Really white spark plugs, instead of the slightly tan color.
The bike is really just an air pump, and you've already got the free flowing air filter...opening up the exhaust just let the engine pump a lot more air through it, with about the same amount of fuel as it had before = Lean. Adding more fuel, when done properly, gives better drivability, performance, and cools the engine down a bit in the process, without hurting the fuel mileage much at all...if it's done right, by a competent tuner, using whatever device he is most comfortable using. The 64K question is always finding a good tuner in your area...
Or, there are good systems out there that tune themselves...lots of choices.