Put in the 58 / 165 jets, performed standard mods (slide drilled, K&N, snorkel removed, needle shimmed .030"), and put on the Supertrapp IDS2 Quiet series on my '05 XR650L. I have 9 disks in; the tuning manual says that 10-12 is the practical maximum, I think. Bike has noticeably more power. Starts right up at 30 degrees F. Pulls strong through the gears. Top-ends at about 85-90 or so. Pulls a very easy wheelie in first and will just begin to lift up the front with no clutch in second. Smooth throttle response; pipe is not too noisy. Overall, I'd say that I'm very pleased. Haven't checked the plug, but I will soon. Interestingly, "Burned" over in the jetting forum said that with modern fuels, you can't reliably tell a rich/lean condition from the plug color any more. But, based on my gut feeling, the bike is running pretty sweet right now. One guy a while back said that with this setup it should go past 100 and get it right up EASILY in second with no clutch, but I'm a little suspicious of his claim. Opinions?