mptoledo-
check out this
comprehenisve guide to upgrading the Boxser's sound system. Pick and choose what you want to install. The full guide was written by andy_m over on renntech.org
also,
here is a template i made for the door speakers to replace the stock 5.25" tuned ports. DO NOT waste your time trying to find better 5.25" speakers. It's impossible w/o a TON of power. Just bite the bullet and go w/ either 6.5"/6.75" or even 6x9" for the doors. The rest my friend is up to you.
