Will add more details and pics later, but it is up to you if you want to remove the plastic sheet. I am going to use sound deadening spray and cover all of the holes on the inner door skin. On the outer door skin I used two layers of sound deadening mat. Don't separate the box. Just take the time to cut on it until the speaker fits. I even filled it with cement to deaden it. When the speaker is playing the mounting surface should not vibrate along with it. Will post pics tonight.
Ok, here is how I did the doors and some pics.
1. Remove door panel, plastic barrier, stock speaker, and box. Remove speaker grille. Be very careful with the pegs, not to break them off. Easiest to just cut the push on metal tabs and get new ones from the hardware store.
2. Using ¾” MDF, cut out a circle that will fit in the depression on the back of the door panel. This will serve as the new speaker mounting ring.
3. Shave off the lip and vent of the speaker box with a dremel and cut off blade. I use the fiberglass blades.
4. Remount the speaker box and hang door panel. Slide the MDF ring up into place so it fits the depression in the back of the door panel. Mark the four holes that the speaker grill pegs stick through onto the MDF. These marks will serve as a centering guide to cut out the center of the MDF for the speaker. I also drilled a hole where the marks are so when the grille is mounted, the pegs will have a place to fit. When finished the MDF ring will be flush up against the door panel and the pegs will hit it unless you make small holes for them.
5. Take the MDF ring out, lay your speaker template out centering inside the peg marks. Mark and cut out the center. You can router it now to flush mount the speaker.
6. Place the ring back in between the box and door panel. Mark the area you need to cut out of the box. The back side of the box will vary depending on the speaker magnet. Also make reference marks to the orientation of the ring so when you attach it to the box, the peg holes line up with the holes in the door panel.
7. Do the necessary cutting on the box to get the speaker to fit and clean it up.
8. Attach the ring to the box with silicon and screws or small bolts. You may have to countersink them a little so they are flush if they are under the speaker instead of on the outside of the ring.
9. I filled the box with cement to deaden it.
10. Mount the speaker. I added some fiberglass on the back side of the box since I had cut out a large portion of the box for the magnet. Aluminum foil works great to protect what you are fiber glassing around.
11. Hit it with some paint and bolt it in. I popped out the plastic pieces in the door and will be using bolts instead of the screws to mount the box.
12. Once mounted I will run some expandable foam around the perimeter of the box to seal it to the door. Also covering up any other holes. Foam mat from partsexpress works ok on the big hole.
13. I also put two layers of sound deadening mat on the outer door skin and will be using deadening spray on the inner skin. Just too many holes, contours and things in the way for the mat.
SPEAKER GRILLE
1. Parts express 6.5” grilles will fit inside the outside part of the oem grille. You just have to disassemble the two pieces, then silicon the new grille to the outside ring. Then remount it to the door like factory. Cover with grille clothe if you want.