I installed 6x9" speakers in my front & rear doors. Most audio stores sell speaker spacers in various thicknesses so you don't have to mess with the weatherstrippng that I've read people are using. You have to cut the rear door sheetmetal if you plan on running anything bigger than 4". So I figured, why not just cut it to fit a 6x9. I bypassed the o.e. amps and ran my own system w/ amp power running 4 6x9's in the doors, and that got all the sound I wanted. That was until I removed the doors. Then I installed 4" Coaxial speakers in the dash and put 2 of the 6x9's in the rear tailgate.