Just did mine at around 20k, 2 exhaust on front were out of spec and all but the rear inlets were on the tight end of spec, was able to swap a couple and bought the rest of the shims but all valves are now right in the middle...the bike previously never felt right going over 60mph, now I struggle to keep it under 80! That is if I don't watch it, she just zooms ahead, wonderful change in her! Not sure if they were ever done before I bought her at 14k miles, I'm assuming not to be honest as the bloke who sold it to me told me it had had a full service with a receipt to prove, the receipt showed oil and filter and nothing else! Typical sales B.S.!