I had a 2011 MM ISF and I miss the sound (especially the rev matched downshifts) EVERY SINGLE DAY! PPE and Borla sounded great if you could live with the 2k rpm drone. One of the first things I noticed in the Stinger was how quiet it was vs. the ISF. It was one of the reasons I bought it, that and the ISF drone, and 2006 "tech" had to go.I drive a Lexus ISF which has a V8 and I have headers and full exhaust no cats lol so maybe my sound taste and ears have been mutated lol ....
I like the idea of switchable exhaust for the Stinger (and the ISF). Switchable keeps you off the radar and makes highway driving tolerable. Love the TT whistle though!!