You need to buy out the lease or return the car to original. Your lease company OWNS the car are while what your did is nice (and costly) they will have to get it back to factory original.
My 2015 has the upgraded Shaker system. I have no volume issues with Spotify. The system is good enough that I can tell the difference in lower bitrate MP3s and older/poorer quality recordings.
I have the upgraded system and Spotify sounds great. You can get the high quality streaming option if you pay for the service and also download 3000 songs in HQ 320 bit on your phone.
I think your plan to get the Track Pack is a good plan.
You will get a great deal of value out of the strut tower brace package.
http://www.americanmuscle.com/frpp-strut-brace-2015gt.html
I think tire pressure makes a big difference on the g2 tire. I think they aren't as firm as the Pirelli summer tires I had. Running them at 36 pounds they feel quite different than at 32. At 32 they rode nice and gripped great but seemed kind of loose feeling. Not a big surprise. What...
Mine were running at 35 but I read a review somewhere about a BMW with these was running at 40.
Nitto replied when asked and said check the door for recommended pressure...kind of sidestepping my request.
Bought a set with 255/40/19 on front and 275/40/19 rear for my 2015 Eco with PP. They are much nicer riding and quite a bit more quiet. I am not sure how much of that is due to the old summer Pirellis being worn down (had 14500 on the set). VERY happy with the new setup.
What tire pressure are...
Passed a Lamborghini Gallardo this morning going to work. He was caught in some traffic and made sure to get through traffic to pull beside my Competion Orange PP Ecoboost to give me a big thumbs up. Made my day before he blasted on.