I've had bikes with Power Commanders III's, SERTS, Power Commander V's, and truthfully, for just a stage one, they didn't do very much at all. Some caused me all kinds of headaches. Some made my bike run much worse. I've been told by several HD techs and independent mechs, one with over 30 years experience, that bypassing the 02 sensors, which most aftermarket tuners do, isn't a good thing to do. My current bike runs great on the simple dealer download. I had all sorts of problems with the "tuners", so I decided to forgo those with this bike. I'm perfectly happy with the download. Works fine for just slipons and airbox. The mechanics I asked said tuners are "overkill" for just a stage one. Everyone I talked to said the download is absolutely working great on their bikes. Everyone except people on internet forums anyway! Maybe, if you plan to do more than that, a tuner might help. But, seriously, I know dozens of people running the download, some for lotsa miles and lotsa years, and they had zero problems and are perfectly happy with their bikes. Who on here has a tuner, and who is running just a download? Happy with what you have or not?