During the week I installed the JD Jetting Kit and an FMF Q pipe onto my 03 WR450. I finally got a chance to test it this morning. All I can say is that Dave Dialogue is right: Holy Crap! The combination of these two is like riding a totally different bike. The midrange is so snappy and responsive now that it's amazing. The bike will pick up the front end easily now. Prior to this the bike ran fine, made good torque and was well mannered but the throttle response was a bit mushy. Now, it's still well mannered (predictable), but much more responsive. I'm very pleased with both products and the installations were pretty easy. well... as easy as anything can be when working on the rather cramped engine spaces on this bike - they crammed a whole lotta motor into a small space. I would definitely recommend both products to anyone wanting to up the performance of their WR450. The Q is definitely louder than the stock pipe with the GYT-R insert, but it isn't obnoxious. I actually like the exhaust note of the Q better. The Q is definitely lighter than the stock pipe also - I would guess about 3lbs. less.