I dont know about the 997.2 but on my 997.1, the PSE sounds really good with the plug disconnected at the back. Ive also read in a few places that it apparently gives you just under 10 hp (although unconfirmed by Porsche due to legality issues I suppose).

 Just ordered the headers and air filter from the X51 kit, hope that gives me a bit more noise and maybe a few ponies too if im lucky.

My friend got his 997.2 about a week ago and I must say it doesnt sound too shabby for a stock exhaust C2S. Its definitely quite a bit louder and sharper than a stock exhausted 997.1 version.