Screamin' Eagle Pro Super Tuner
Get ready to study, and dust off your chemistry and physics books if you want to eek out everything this tuner can do for ya. On the other hand, you can let it do most of the work and just ride. Nothing permanently installed. Access to the adjustments yourself instead of having the dealer do it for ya ($$$).
I am happy with mine, but then understand I do still own a pocket protector (under the jacket...) and I think I have a slide rule in a holster somewhere.
...and I used to think my Sportster was heavy...
A Harley will get you through times of no sex, better than sex will get through times of no Harley.
SE Heavy Breather
V&H Monster Ovals
SE Pro Super Tuner to make the above play nice together.