Two of my friends in S. CA have the Big Bore Kit's on, One was the 912ULS 100hp that went to around 114 and made a good bit of difference in his ability. Another was the 912 UL 80 hp that went to 104hp and it made a major difference in his performance, Wayne Flemmington of Rotax Service located in French Valley is installing these as well 951-255-9144, Once mine is ready for topend I will be putting it on.