I went up two teeth to a 43 tooth rear sprocket when I recently replaced the chain and sprockets. I feel as though the bike is smoother (it is obviously pulling more revs) and it is a little bit quicker in any gear. I rode it 14,000 miles with the stock gearing and always felt it was overgeared with the stock 17/41 combo. My DL1000 likes to run above 4000 revs and in 6th gear at about 4000 RPM, I am showing an actual 61 MPH on my GPS. The change in gearing did cause an even more inaccurate odometer/speedometer. At 75 MPH indicated, my GPS shows 65 MPH actual speed. The odometer is now approx. 5.5% fast. I haven't noticed any reduction in gas mileage since I have only put about 800 miles on the bike since the change. But hey, it runs better and I would do it again.