I had great luck with the 391s on my XMs but can blow any of them on my G4s, had a 2017 and 2018 with about 1500 miles each and went thru 12 belts in 17 and 4 in 18...just way to many. My XMs I never blew belts or very rare....Im now older and slower riding the same zones...hope 19 is better or I will be thinking switch teams which is a hard thing for me:juggle: