As Jase has said, pop the door cards off mate and you will see how easy it is to remove the speaker enclosures.

i have/had Focal Poly kevlar components within mine, all neat and tidy and you wouldnt even notice they were any different unless you peered closely thru the speaker grilles.

pop along to any decent car stereo shop and they will probably have something off the shelf that will fit directly into the standard speaker pods.