+1 on the Infinity reference speakers. I had the opportunity to listen to several competing brands at the Fry's display, kicker was one, and the others sounded like the kicker which were ok, but not really impressive. The infinity speakers opened up the sound big time, there was no comparison.
I did sacrifice the old boxster speakers using a dremel tool to cut the original speaker so I could use it as a mount for the new speaker, a heat gun to bend the speaker connector into place, and then soldered a wire from the original speaker connector to the new speaker. I did a lousy job of photo documentation, but it is straightforward when the parts are all laying on the table.