Im interested to know how your installer partly opened the blocking plate but to answer your questions:
With the valve closed there is no exhaust flow through the outer tailpipes. With the valve closed it will be around stock decibel wise, maybe slight tonal differences. With the valve open it will sound beastly, especially if matched with a N55 midpipe or MadDad, with exhaust flow through all tail pipes.
Heres a video posted recently of the akra+N55 pipes.
Also, two great threads with everything and anything you need to know about how the wireless kit works.
http://www.1addicts.com/forums/showp...21&postcount=4
http://www.1addicts.com/forums/showp...0&postcount=12