My N15 Pulsar didnt come with speakers in my rear doors, i have already upgraded all speakers in the car aswell as changing the 6.5" parcel shelf speakers to accomodate 6x9's
Here is how i installed speakers in the rear doors for under $100
Step 1 : remove rear door cards
Step 2: Mark out where you want to put the speakers, i mounted the speakers to MDF speaker spacers
Step 3: Measure your door card, i made a quick template
Step 5: mark where to cut then cut the hole for speaker
Step 6: CUT! measure twice cut once remember!!
looks a little rough but had to use a angle grinder as my dremel broke. doesnt matter i sanded it down and you cant see the cut anyway
Step 7: Mount speaker spacer to door using the 4 screw holes made for speakers
Step 8: Use 4 screws to mount speaker to speaker spacer
Step 9: TEST!
Step 10: if all works then mount the door card back on the door and run the wiring, i ran the wires to my amp but then changed it to the wires on my 6x9s as it sounded more clear and louder.