I highly recommend Daves' carb mods. VERY easy to perform.
My '03 XR650L also has a W2 exhaust, larger fuel tank, vented airbox, and has been de-smogged. The bike flat out RIPS, will do 85mph all day two up with my 16 year old daughter on the back, and gives an honest 50 mpg.
Put it in first gear, and it will idle along thru almost anything.
Wonderful bike. Everyone can bash the 650l's weight til the cows come home, but I don't care. Damn thing will go anywhere, and they are indestructable. No radiators or water pumps to worry about either.
Life is not measured by the number of breaths we take, but by the moments that take our breath away.