You only need it if DynoJet does not have a map that matches your setup or you don't have a custom map for your bike. My wife and I have a Can-Am Spyder for touring. I have a PC5 and AutoTune on the Spyder. I removed the catalytic converter, added an exhaust and opened up the intake. DynoJet did not have a map to match that configuration and I could not find a local shop that could create me a map because they couldn't get the Spyder on their dyno. The last resort was to add the AutoTune. DynoJet told me which base map to start with and the AutoTune made the adjustment over that. Now for my VFR, I also have a PCV, but no AutoTune because they have a map that matches my configuration.