I cut the throttle stop 23 mm on my 2000 wr400, cut the gray wire, and pulled out the smalle insert baffle. The bike rips. I'm very glad I bought it. The more I look at it the more I realize it has no miles. No paint rub marks near pegs, a true 700 mile bike with orig. tires. There is a pretty bad bog when you nail the gas at lower rpms, but I went through the carb and the guy had a 160 main jet, a 42 pilot, a 65 air jet(or whatever its called), and the stock odbrs in the 3 clip. I need to get it rejetted for my altitude so i'm thinking. 168 mj, 45 pilot, leave needle,and no clue about the air jet. Is the chrome outer insert meant to be removed or does it cause too much of a loss in back pressure( the one held in by three bolts not one). Noise doesn't matter for hillclimbing. on the ranch. Also does the bk mod solve the bog at low rpms pretty good? thanks ps does the rear brakes on these things suck naturally. It seemed as if it really liked to lock up. rotor too small?