I'm pretty sure the owner's manual warns against prolonged operation of the engine in stealth mode (went thru the manual quickly, but couldn't find the reference).
Anyone who has done a 5am start-up in stealth mode knows the valves open briefly (you cringe and try to think of all the nice things you've done for your neighbors). I figure this is necessary to 1) warm up the cats per EPA requirements and 2) help the car start quickly and not foul a plug.
IMO, bypassing any valve opening could lead to issues caused by excessive back pressure as Chutzpah mentioned.
I like the factory set up that I've fine tuned to keep the exhaust sound management in Track at all times, no matter the suspension setting (don't have to get up at 5am anymore!), but I really enjoy how the NPP will still close the valves at light throttle and then open them when you give her the GAS! With a Rev matched downshift, you can surprise folks from time to time. I guess I'm still just a kid at heart- or juvenile delinquent!
