One more "bought (leased) off the lot" here--although I think the NPP sounds great, I couldn't find a car configured the way I wanted: V6, M6, NPP, w/o RS. I dislike the 20" wheels for DD use more than I like the NPP sound.
I have considered putting an aftermarket exhaust on it, but probably will just leave it alone. If I want to make noise, I will ride my Ducati 750 F1 or BMW S1000R.