"Isolated Drive System". It's like the "cush drive" in a lot of metric bikes. The rear wheel is fitted with a mechanical rubber-like device sandwitched between some vaned metal gizmos, all enclosed in one housing and placed on the axle between the sprocket and the hub itself. The idea is to dampen out some of the driveline "jitter" associated with each cylinder's power stroke impulse.

Here's a link to a search I did for the term "IDS" used in thread titles within the Touring forum:
https://www.hdforums.com/forum/searc...archid=2228950

ETA: As 6 gun says, it's often not a big help and can have it's own problems (just another device that can break) so unless you feel that you need one... The reason I mentioned it was the fact that some people with '07s do feel like they need one so it's an item for you to be aware of in response to your original question.

 

I have the same bike, the entire exhaust on mine is custom from stock. stock exhaust converted to true dual, stock mufflers with custom buffles, hi-flow Zippers air cleaner. the ECM is Thunder Max with Autotune the best investment. Thunder Max is pricy but well worth it.