I had about 15k on them, I now have about 40k on them. When I took it in, they check and found the guides still in specs but right at the limit. So the shop got approval from BD and rebuilt them with what I was told was S&S components but they kept the TP Rocker Boxes. The shop had been changing them out before with S&S Boxes, but I guess BD made changes or something as more were done or they investigated further, who knows. Just know they were changed so far so good. If I can find the sheet from the warranty work, I will double check the parts list, but I understood on more than one occasion from the mechanic/service manager that it what was done. Possible that I misunderstood or was told wrong, but I can verify that I have the rollers, different springs than original, and TP Rocker Boxes and I have no issues that I know of. While they had it, they changed the cam to a 600 so the spring were also changed.