For those r6 riders out there, I have an 02 r6, which has high miles on it (around 16000). I recently got it out of the shop for the 15k mile tune up and seemingly overhaul, but over the past week, I've noticed a bad vibration which only happens around 5500 rpm. any clues? I only use Chevron premium, so I doubt it's knocking, I keep my oil changed frequently, and have not done anything to it other than use it for transportation recently (sadly). Any ideas before I take it in and shell out shop costs?