Used to be that it was well-known that the best bang for the buck in car audio was speaker upgrade. Bose sort of complicated all that.

I'm thinking of getting a base "S" model. I don't really want leather seats, etc., etc. I know people here have upgraded speakers, but I'm not sure if that's true only for the Bose system.

Anyone care to comment on their speaker upgrade? Base, Bose, or otherwise? Difficulty?