check out THIS thread on that subject. I haven't done anything yet on mine, but have been thinking about it for quite some time...
Since it comes back time and again, this MIGHt be something for the Hall of Fame...
Wouter, Have you decided on a speaker configuration yet? We picked up the USA-630 radio and still contemplating the speaker set up. The thread above mentioned some speakers under the seats (thanks for posting that). I see in CI they offer UNDCOVER Speakers that should fit under the seat (need 3" clearance)and they have a dual cone front speaker that fits in the original dash location. We wouldnt have to cut the kick panels or the rear piston covers if we went this way.
Has anyone tried the speakers under the seats? Finding 6x9's like Vikki mentions for the rear, with less than 2" depth has been diffacult.