http://www.nengun.com/apexi/active-tail-silencer installed it and my car is quiet!! but when i get on it, it opens up and is almost as loud as it used to be
this just seems like it would be a nightmare for your ECU tuning with the exhaust volume changing every time you get on the throttle. When i put on my fixed silencer i know i lose a good 30 hp and i usually have to reset the ECU for the timing to come back in any short manner after it's off.