I agree with the wr450f guy...I've got the very same exhaust on my 2000 and then dynojetted. The entire process took 3 hours in my garage and it certainly hopped it up. Low end was most improved, the mid was torkier and the bike will actually do 100+ fairly easily now at 6000 ft. Only complaint I had was that the yoshi was way too loud. A great sound (kinka like a rocket), but it affected the comfort level of the bike. So I had to build a custom baffle, to shut the 100dB sound off. Jetting, exhaust and airbox mods are all I've done, and probably all I will do. I think if you need more than that, you should probably get a different bike like the xr650r, which has a bit more compression and is a few pounds lighter. Oh, the tank and cap on the 650L have a combined weight of somewhere between 200 and 250 lbs (I hope you know this is an exaggeration ) and because the tank is only 2.8 gallons, it's the only complaint I have about the bike. I guess I'm saying the tanks days with me are numbered.