The engine is pretty new so thee is little information or even products out there yet. We are left with just upgrades that were already available to other bikes.
1.) NGK CR7EIX Iridium plugs
2.) Previous low flow mufflers
3.) High quality Synthetics for the motor and final drive oils
4.) (K&N air filter mods) Although I haven't seen one yet.
5.) Rollers to get the bike on the pipe
6.) HiT Clutch to get the power down quicker and more in the pipe.
7.) Power Commander to tweak in all the new harware.
8.) Not sure but you probably could "DarkSide" one of these.
Of course these all effect MPG and ride etc. I am extremely happy with the ride it has now. every 50 or so miles it seems to just run better. One thing I've noticed with the Iridium plug now is at slow speed manuvering you have to watch the throttle. Too much out of a slow speed turn (3-5 MPH) and it kicks too hard if you do not watch it. Throttle responce is notably faster and the seat of the pants can tell. It will not be pulling a wheelie any time soon but it can straighten you out of that turn before you wanted.
My mods will be the minor ones. Iridium plug (already in), Full Synthetics and maybe the rollers. The rollers have yet to be determined as an upgrade. I will wait until at least 3,000 miles to see where the bike ends up. My best guess here is, with Dr. Pulley Sliding Rollers, 20x12 14 GR to get the bike on the pipe for top end and streetable high performance 20x12 13Gr with a HiT clutch.
Even with full mods, if you are like 170 LBS, don't expect much better than just under 6 second 0-60 MPH. I doubt we would see sub 5 seconds, but I could be wrong as the waters haven't fully been tested yet.
I do know my cousin and I compared this to his wifes Piagio MP3 400 and the DT felt stronger 0-65 MPH (form standing start and rolling). That was even before the new plugs. With the plugs and break in milage the preformance has improved even more. To be fair though the MP3 only had 350 miles on it. I know it is way stronger that the carb'd Honda Reflex he had with 28,000 miles on it, just the next class of power.
I am posting everything I can think of for two reasons.
1.) so people can decide if this really is the bike for them
2.) to increase a knowledge base for current owners.
I hope other post experiences with changes as well so we can all get the max out of our bikes.......................