My buddy has '00 R6 and is thinking of having me jet it for him but he wants to know how much this will help performance. The bike has a Muzzy slip on and -1t front sprocket. Any feed back would be very helpful.
The gearing won't have anything to do with the jetting.
You want to restore the air/fuel mixture balance that may have ben upset by a free flowing exhaust.( admitting more air with the same amount of fuel )
To do that you really need access to a dyno or exhaut/gas analyzer otherwise you have to guess at it and see how the plugs/running conditions respond to the change.