Heres what i have done to my 07 DR650 at 10000 miles did the air box mod, FMF Q2 Quiet version, 150 main jet from Procycle, Mixture screw adjustable at 1 1/2 turns out, KN airfilter with foam pre filter, 4th position on the clip, no extra hole for improved response.
The results are alot more mid and low end range, it does have some light pops on deceleration but not to bad. I get 50-55 mpg and it is a blast to ride now, i have a hard time keeping a rear tire on it! It does every thing i ask it to has been very dependable. It will do 70 mph down the gravel or road fully loaded. I love this bike.