I went to AI Designs (aidesign.com) to get my 18" wheels + exhaust installed and windows tinted... plus detailing and scratch removal.
They did an amazing job and were very personable. It seemed like everyone in the shop knew who I was when I walked in. Plus they pay special attention to detail. One of my new wheels had a tiny scratch on the side... and they went ahead and ordered a replacement before I even knew about it.
Walk into their shop and you'll see them working on a variety of high-performance European cars. Plenty of Porsches inside... and on one day I was there, they were outfitting a Mercedes Benz Limo with a Super-charger boost kit with custom interior modifications. I felt very comfortable leaving my MB in their hands.
If you're in the NYC area... highly recommended A++++.
Ask for Gil!