Hi Spinner Dan, we have 2 XT660r's, 1 with GYTR cans, the other with a Metal Mule 2 into 1 system. Not sure why, but the GYTR bike seems quicker and smoother. (Doesn't sound as good though) They were fitted when we got the bike, so don't know what it was like before. We live on the Sunshine Coast, so if you need to look or listen, get in touch with me. Curt