I currently have the same problem
I have pulled my speaker's out to
find the the little amps.
Problem 1 :- without the amp's you loose at alot of power/volume
Problem 2 :- the rear door speaker's are also powered by the amp
Problem 3 :- odd sized hole for a 6 inch speaker (will need 6.5 in)
Problem 4 :- lot's of rewiring
Problem 5 :- speaker depth
I am going to buy a good quality set of 6.5 componet speaker's checking
the magnet size as I go. Then my intension is remount the amp in the door
(will need to bust up the old speaker) and extend the speaker wire's from the
amp. The wiring loom has enough length.