Been there done that.
You will see very little difference with just the PCIII and no muffler changes. I would say that it is not worth the money unless you replace or modify the exhaust and intake systems.
As delivered from the factory it is tuned to optimize economy, performance, emmisions and fuel economy. For a commuter bike it would seem that stock is most appropriate.
And on top of all that, if it is what you want to do use the stock Versys map that comes with the PCIII. If you install an aftermarket can give me a shout and I will get you a couple of maps that I have.
Japanese scientists have created a camera with such a fast shutter speed they now can photograph a woman with her mouth shut.