Got it from BikeBandit. Really like it. It came with 8 discs, which I tried first. Loud! Greatly improved the mid-range & high rpm power & didn't reduce the low-end torque. Then I tried 6 discs, a little quieter & less power. I'm happy now with 4 discs, which is a little louder than stock & makes more power but more importantly it no longer sounds like a moped. Runs best now with a 152.5 main jet & no need to alter the 1/2 spacer or pilot screw, 1 1/2 turn out. Install was quick & easy, though remember to remove that flexible bushing on the header pipe first or it won't slide on far enough to align the bolt holes. I love the sound! Didn't want loud, just wanted to turn down the treble & crank up some bass.

No backfires. I dreaded the possibility of tweaking the white spacer again but it didn't backfire on the ride to work & back today. I'll be out riding with my neighbor & his riding club in a few minutes & I'll see how it goes. Not sure where we're going or for how long but it should be fun.