I had 997.2 with stock exhaust system - which I think we all agree is jut too quiet. My first mod was the H&S bypass which effectively replaces the real silencer with a crossover pipe. It made a slight difference but still not quite loud enough.
I deliberated long and hard about what to do next. I got a quote from local OPC for a full PSE fitted for £2,034 - but ultimately decided to go for the Top Gear stainless steel valved silencers at around £900 (discount may be available) which I wired into the Porsche PSE button on the console (see my other posts for this)
So my end result is Top Gear valved silencers plus H&S centre bypass. Really pleased with it. It is not too loud at all - just the way it should sound. I normally drive with the valve open (loud) but it is quite nice to be able to turn it off on the mornings I leave for work at 06:00 am.
It is the small things that make a difference - and I really love just pushing the button (which has a nice icon of the 997 tailpipes) seeing the LED light up and hearing the exhaust note change - always puts a smile on my face
The overall consensus is that PSE on its own on 997.2 (without the rear silencer bypass) is not worth it
Hope this helps