I did the Brentune on my 2016 recently and made a short tutorial video on the process. I can say that the difference in performance was significant for me and worth the cost. It truly woke my bike up, made the throttle much more responsive, smoother and removed all the flat spots in the RPM range. I'd strongly recommend using the handheld tuner from Brentuning as it allows you to install the tune without disassembling the bike and mailing the ECU to Brentuning. The whole process took less than 30 minutes. It's very simple and would be difficult to screw up unless you set out to do so.
If you have any specific questions for me, please just ask here and I'll do my best to answer.
My background is:
I've been riding motorbikes for nearly 45 years. I race both road race and woods (enduro style events) as well as compete in Trials events local to me. I run a small shop from my home where I build custom track bikes, suspension for street, track and woods bikes as well as perform performance work for my clients. I've owned in excess of 100 bikes and usually have 5-12 bikes in rotation at any one time.
I like bikes and most people associated with bikes. I keep almost nothing stock. That's it!
, you're a braver man than I am... I read about the tune for <'16 K1600 but Bren couldn't provide any proof that the tune does much, if anything, for the older K1600. All they told me was to expect 7-8 hp increase, which for that kinda money is mighty hard to justify. I may rethink decision if I ever see a before/after dyno run.