OEM there's dozens that use something similar, Dancing horse, Maserati, Bentley, Jag, Aston Martin and so on. Some, like the 360 though, i think are for sound.. not noise suppression.
I've a mate with one, though theres a 4" "Y" pipe. Closed the zhaust works normally, open and it sounds like an open pipe bridge ported 13B *cough* ... So he has an option of loud (100dB) and even louder...
Most are stepper motor controlled, so you could make it open (any angle) by any system with a spare output, like an aftermarket ECU. Im sure a simple PIC could help those with OEM ECU's.
I figured most people used a Y pipe, and diverted the exhaust gases straight to atmosphere, but it seems not of late. The large 3.5" - 4" units from teh US seal COMPLETELY for this reason.
BTW, I would expect the roadside RTA to rape you dry if caught.
I would be VERY cautious of exhaust temps (straight through, non Y style) when cruising on the freeway, as the back pressure plus closed loop lamba correction, would make for some very hot exhaust valves i would have thought...
Juz my thoughts