For my subs [pair, 12" Kicker Solobarics] and amp [Cadence 6Ch Class A RMS: 75Wx2 @4ohms (front) + 150Wx2 @2ohms (rear doors and rear deck) + 450Wx1 @2ohms (subs)], I have constructed a box out of 3/4 MDF. The enclosure will be sealed and filled with the appropriate amount of polyfill. The box is angled on the front edge to match the back of the rear seat. Thus, the subs will fire into the car (not the trunk). The front of the box will have a decorative finish witch is composed of multiple layers of MDF, some of which are fiberglassed over and then painted. Looking at the bottom left picture, the "oval" has since been fiberglassed (see bottom right picture) and then painted gloss black. The area outside of the oval will be covered with a small amount of padding and then a fabric which matches the rear deck material. This portion of the enclosure will fit perfectly to fill the opening to the trunk. If you notice that the middle section of the oval is recessed, this is where a piece of aluminum cut to the Audi rings will reside. Look in the pics at the bottom of this page to see the rings. These rings are designed such that the outer two rings share the same axis's as the subs, and thus are centered about each. The rings act as a speaker grille.
This router is my friend :o)
The amp is flipped around and mounted to the front side of the board with the ring siloette cut out. There is a 1/4" plexi piece between the amp and the board. The amp also has a plexi bottom to it.. Below that are the crossovers for the 3 sets of compnent speakers. Also, the enclosure is a size such that it does not interfere with removal of the spare tire. I have since added (3) 1 farad capacitors, and mounted everything in a temporary fashion, until I know exactly what I am going to do.
The front doors will contain a set of Cadence 5.25" components. They have an aluminum alloy mid, silk tweeter, and Xover. I purchased the MB Quart adapter rings and had to modify them to fit with the large magnet (20oz) structures. I also had to modify the doors slightly as well (dremel away some plastic). The tweets are mounted in the stock location. Look at the stock tweets (foam!) compared to the Cadence ones.
I do not have the Bose upgrade, so thus I have no stock speakers in my rear doors. I purchased the stock speaker grilles if I did have speakers there. I mounted my Cadence 6.5 components behind those grilles and flush mounted the tweeters. Originally I mounted the speaker to the door panel and later found it easier to mount to the door frame instead.
For the rear deck, I mounted another set of 6.5" Cadence components. I purchased the MB Quart speaker adapters to aid in the install of the mids. No mods here other than a little foam tape to avoid some rattling. For the tweets, I modified the stock grille in a way such that the tweet just pops through an unused portion of it. I painted the tweeter grille to match the stock speaker grille.
I'll be using a Pioneer Fold-Down CD Player along with a full-DIN EQ in place of the Symphony unit. I will be recessing these and then covering them with a fake front plate which will contain a Concert headunit face. This has been quite tedious and is currently in progress. I needed to file off some parts of the cage that's in the last pic. Well, as I started, I realized that it was not black plastic, but instead painted aluminum. Instead of a quick dremel job, I got out the metal file and a little elbow grease.
The first pic shows some extra speaker wire in the kick panel. This is because I did not leave any slack in the door, so should I need to remove the door, this will allow me to. All speaker wire is 12ga. The other 3 pics show where I drilled through the firewall to route my red 4ga power wire.
Here's most of the stuff I had as I began working
I plan to mount my Pioneer 12 disc CD Changer in the stock location. some modification may be needed.