Like 1949 said the difference for making 6th more usable after the tune had to do with the engine lugging. Basically the tune richened the fuel mixture so the engine gets more fuel making it run cooler and depending on the tune, the lower rpms smoother. I wouldn't consider it to have fixed any vibrations unless those vibrations you are talking about are due to lugging the engine. If you do just pipes or air cleaner you probably don't need a tuner. If you do both you may still not need a tuner, but the benefits of the cooler engine and overall smoother running are worth it to me. And I personally like the PV because it just flashes like a SERT without having a piggy back module. I don't have room under the seat for anything else. If I trusted my dealer may have a different opinion on which tuner to do, but since they have screwed me too many times I don't let them touch my bike anymore, and the PV has great support from where I purchased it.