I started this project by reading everything Steve from Subthump had written on C5. It took him many months and what he came up with was a complete wire harness kit and a mounting kit. If you go this route here is what you will need.
Amp: JL HD 400/4 Cost $400 on Ebay.
5G-FARK wiring kit Cost $99 Subthump.
Amp mount kit Cost $12 Subthump.
Wire, 6 ft of red and 4 ft of black 8 gage min. w/ 2 ring terminal ends. (I used 6 gage)
Fuse holder for 40 amp fuse. Cost $13 or less (I went to a car stereo store)
2 RCA shielded patch cables, male on both ends. 1 ft if you can find them that short.
I bought the amp that Steve recommended. There arenít very many that will fit in the same space as the factory amp without major modifications.
I will skip over some of the details that are covered in Steveís installation instructions that you get with the wiring kit and focus mainly on the power supply part.
First letís find the amp. It is on the back wall of the trunk on the driverís side. Take everything out of the trunk down to the battery. I decided to remove the rear trunk panel because I will have to do it for future mods and I wanted to see how hard it is.
If you donít have a set of plastic trim removal tools, go buy one. Or take a metal pry bar and wrap it with tape.
Unscrew the 6 cargo tie down lugs.
Starting at the ends, roll off the weather striping. When you get to the little flat spots, (pic 1) get the pry bar under the panel and lift. You will hear the clips pop out. Thatís it.
Pic 4 shows the panel removed and you can see where the clips are located.
Next is the molded side carpet section. I didnít take it out completely. You only have to remove 2 fasteners then you can fold it forward and use something heavy to hold it out of the way. The one on the floor screws off and the one on the top is one of those tree fasteners that you end up cutting off. I didnít bother replacing it, yet. (pics 2 & 3)
So there it is. One nut and 3 wire plugs and it is out.
Now follow the instructions for the wiring kit and wire the outputs, the trigger wire and the power. You should also plug in the RCA inputs.You want to have all the wires in the amp BEFORE you mount it because it is tight in there and you cannot see the bottom of the amp once it is mounted. Both the X2 and the X3 plugs are marked with front/rear, L/R channels. Channel 1 is LR, 2 is RR, 3 is LF and 4 is RF. I put a small dab of solder on each of the wires so they clamp better.
Tip: Mount the amp as high and to the left (inboard) as you can. All of this wiring and mounting can be done on the bench.
When you try to mount the new amp, you will probably find some interference from a large bead of chalk. (pic 6) Take a razor knife and cut away about ĺ ď or so and scrap it out with a screw driver.
The instruction for the amp say to find a good ground so I thought the easiest way to do that would be to go back to the battery.
On my first try I ran the wires as directly as I could. Then I tried to put the trunk back together. The big foam hat would not sit down. So pic 7 and pic 9 shows a route that will not interfere with the foam hat. Pic 8 shows the foam in place.
The plastic cover that covers the positive battery terminal needs a small notch carved into the side so the power line can be mounted. I just used a side cutter. (pic 10) This picture also shows where I mounted the fuse holder.
This amp came with the input sensitivity (gain) all the way down. Like Steve says you don't need much at all.
Hope this helps. Any questions?