
Yes. The company that makes it tells you, that once you getting your jetting dailed in like you like it. From there you genraly jet down 2 sizes on the main jet. I had 1 on my old 300ex, & put 1 on my sons 400ex worked great! But I still don't see much room for instalation on my YFZ 450. It is EASY to rejet from there; if need to just loosen 1 scew w/ flat head scewdriver the turn the clicker left or right to rejet.
You also have 5 differnt setting with it! Never had rejet the main jet again. EVER! I think if you could install it on the YFZ would you see WAY less questions about jetting! May I'll take the 1 off my sons bike & see if it fits, Then do a post on it.