Here's my last update on the 131 upgrade. I rode the bike down to bikeweek and back, all together about 2500 miles in 5 day's. On the highway, ran it consistently 80 to 85 mph, the bike was basically loafing around 3000 rpm. Great to have the awesome roll-on acceleration to pass vehicles effortlessly. Averaged about 175 miles between fill-ups and generally put on about 4.7 gallons. Worst gas mileage was 36 mpg and best was 40 mpg. It did seem to get a bit better as I put more miles on the engine. The throttle is sensitive, riding over bumpy roads, I had to be extra aware of my right wrist as a little input will cause the bike to surge. Ran it in 82 degrees in bumper to bumper traffic for about 30 minutes and I can see how it could throw off a great deal of heat in 90+ degree weather. Probably worse for non twin cooled bikes. No regrets, having a blast riding my bike! It is a speeding ticket waiting to happen, lol!