The installation is not hard - I wrote the instructions posted on the Boxster hacks site (
http://iq.dynip.com/~gary/hacks/speaker/speaker.html). I spread it out over two nights with a couple of hours each night.
Sound is a dramatic improvement, but as many point out it is not going to make the sound system become world class. It simply makes it easier to hear the stereo because the speakers are so much closer to your ears.