I just like to add my .02 cents in.......I understand that there's a huge difference of opinion on this topic and answers vary. But my opinion, based on experience, is that the TTS Mastertune is the stuff. All the tuners out there are pretty decent, but the one that really takes the cake is TTS.
Yes, there's a learning curve. Not too hard, but its there.
The nice thing is that the TTS software "learns" your own individual equipment and riding style.....a trip to the dyno confirms that the programs had me so close to optimum, I wasted my money on dyno. And you can adjust your own maps too!
Nice, nice, nice!
6 Harleys so far in my life, and no end in site. This new technology rules!