I own a xr650l with the T-4 exhaust on it. Ordered the wrong tip to start with. Made a call and they had the 4" tip in the mail that day. Told me to just to mail the wrong one back. What service, Extremely pleased. The quiet tip does make a difference in the noise you hear. Still is loud, but it seems quieter. I'd buy it again. my bike runs wide open and it can get pretty loud. Nice to have it a little less loud, easier on my ears.