I have an 03 rubi, I went to crutchfield and I ordered Boston acoustics s45 69.99 for the front, Boston acoustics s55 99.99 new 76.49 open box for the roll bar, Kenwood KAC-5204 amp 69.99 (it fits under front drivers seat) and used it to power a Kicker 10CVT654 99.99 new 89.99 open box for the center console sub. It sounds decent not too great for heavy bass though, but during the winter I put a 12in sub behind the rear seat and the amp powers it pretty good ( i just swap the speaker wires on the amp to power what ever sub im using) sounds good though for under $350
Adapter plates can be found on eBay or you can make your own. the template Is posted in quite a few threads and should come up in a search.
Speaker brand depends entirely on you. Listen to brands then pick a model based on which brand sounds good to your ear. Members here have use Polk, alpine, kicker, and Rockford fosgate and been happy.
Is this just speakers for now? Planning a sub or new head unit? members like to do a new head unit at the same time to enhance clarity. If you add a small amp at the same time youll be happier on top down days.
MTX adapter plates for the dash, 6.5" polk audio non-shallows in the soundbar (I know the shallow mounts have proper mount holes for the factory mount locations...no drilling required). I say go with the non-shallow mounts because the shallows don't take sudden bass hits too well. I tried playing some Silversun Pickups on mine...heavy bass drum hits were popping the speaker behind my head. Had to turn the volume down to stop the pops. Note that I'm also running them without an amplifier right now..could change.
i just installed a new head unit sony xplod cdxgt550ui and it really improved with my stock speakers but i wanna throw new speakers in. im leaning toward 5.25" speakers in the dash and the soundbar. how will the 6.5" fit in the soundbar? do i need adapter plates for the 5.25"?