I'm not using it but it looks like it should be an excellent performer, I saw the rest of the pics of this pipe installed on a bike and that expansion chamber is huge, and it's plenty long enough to make good torque down low as well.
I've been making my own pipes out of kx65 or cr80 pipes and they do really well, but this pipe should work just as well for people who don't have a way to cut up and re weld dirt bike pipes to fit on these engines on bicycle frames, just check out the pictures and make note of how it's routed from the engine and down the side of the bike to be sure it'll fit your frame before buying, but as far as performance goes, this one should do really well.