Just got back from the dealer where they did mods to the battery and side mirrors. There's been a number of posts on the battery enhancement so there isn't much to say except if you get it, the dealer tops off your gas tank, so you might want to keep that in mind.
The real mod I was interested in was the one to reduce wind buffeting. I live near the beach and like to drive the streets with the window down. My previous car was a roadster which I never drove with the top up, so driving around in a car with the windows up is a bit claustrophobic for me.
This modification consisted of two parts; a new "skull cap" over the mirrors and a different plastic piece at the A piller. Aero mods were made to both pieces to reduce the wind buffeting (see photos). There was no charge for this mod. Needless to say, these changes are made at the expense of aero efficiency, how much, I really won't know for some time. However, I'm happy to report that this modification greatly reduces the buffetting. I drove up to 55 mph with the driver's side window down without the buffeting noise. There was still, a tiny bit of pressure buffeting that was just barely noticable. I think this can be pretty much eliminated by cracking open other windows.