I have an 08 CTS with the Bose Amp and Navigation System and wanted to add an aftermarket subwoofer and amplifier to replace the stock subwoofer in the rear decklid.

I used a JL Audio A1400 amplifier (340 watts @ 4ohm) connected to a JL Audio Powerwedge CS112RG-W3v3 subwoofer enclosure. The enclosure fits nicely under the rear decklid in the trunk and doesn't take up too much room. The enclosure has 1 - 12 inch W3v3 subwoofer rated up to 500 watts. I also utilized an MTX Re-Q module to provide a remote turn on sense for the amplifier and also to supplement the loss of bass in the stock Bose equalization scheme.

The stock Bose amplifier is located in the driver's side rear trunk area in the opposite side of the stock battery location. To get to the amplifier you unscrew the 2 black plastic cargo retainers and pry out the two black plastic trim "plugs" with a flathead screwdriver on the driver's side trunk carpet area. Then pry the two black plastic trim pieces surrounding the metal cargo hooks in the lower black plastic piece below the trunk opening. Once the two trim pieces are removed surrounding the metal cargo hooks you can pull directly up on the black plastic piece covering the trunk latch and it will easily remove. Now, you can fold the trunk carpeting covering the amplifier forward towards the rear seats. The Bose amp has 4 plugs (see attached picture) and the plug nearest the rear of the car is the one you need to splice into for the Sub output signal. The line-level signals from the Bose amp are not amplified (there is a separate amp for the subwoofer in the cargo shelf area), the Subwoofer + signal is the Blue with White stripe wire. The Subwoofer - signal is the Light Green with Black stripe wire.

The MTX Re-Q supplies the amplifier turn-on wire (typically blue) by monitoring the signal coming off the front full range speaker signals. Left Front full range door + signal is Tan, - is Gray. Right Front full range door + signal is Light Green, - is Dark Green. 12V Constant and Ground are wired directly to the battery in the trunk.

The stock subwoofer is disconnected but still in the stock location.

The additional bass provided by the aftermarket subwoofer and amp is powerful but not overpowering. I found the addition to be worthwhile and fairly easy to install. The hardest part was researched the stock wiring codes.

Let me know if you have any questions.

Got an pics of the aftermarket amp installed?

The amp was installed on the back of the sub enclosure so that I can easily take the whole thing out in one piece if I need the extra trunk space. This picture shows the amp on the opposite side of the enclosure before all the wiring was cleaned up.

Wow thanks for that!

I have a whole setup in my car w/ JL Z series speakers, a 10W7 (I wanted the 12W7, but the High Output box wouldn't fit, I'm considering switching to a 12W6v2 though because I have that in my old car and the sound is the best quality you can get at that level) and a 1000/1 for the sub and a 450/4 for the speakers.

My setup takes up a good amount of my trunk, and my amps are in my spare tire well. Yours barely takes up any space, so that's great!

Just a tip, if you're looking for a little bit more bass, remove the stock sub because it will give the bass an opening into the cabin.

Gentlemen, I am adding 2 Alpine Type R 12s pushed by 1000w of digital power. Also, I paid for the fold-down rear seat, and intend to use it. Next week or two until I debut the Sapele trimmed enclosure.

Gentlemen, I am adding 2 Alpine Type R 12s pushed by 1000w of digital power. Also, I paid for the fold-down rear seat, and intend to use it. Next week or two until I debut the Sapele trimmed enclosure.

I used 2 own a single Alpine Type R in my 99 Maxima before I switched it out with a JL W6v2.....The type R's are a great sub for the money.

i had 2 Type R's in my old Grand Cherokee pushed by a Hifonics Brutus 1500W amp
i didn't have it anywhere near turned up and it was still insanely loud

pyro and ngiardina- you dynmat your trunk at all?

Yeah, my trunk and my doors are completely dynomatted.

I will be dynomat ultra-ing the floor of the trunk and the underside of the lid.

Where did you find the stock wiring codes?

I would like to add speakers/sub/amp but would like to get at the pre-amplified inputs for the amps.

What did you use for the remote turn-on for the amp? Also, where did you go through the firewall to get the power to the trunk?

What did you use for the remote turn-on for the amp? Also, where did you go through the firewall to get the power to the trunk?

He used the MTX reQ, which autosenses signal coming through the speaker wires, but the remote lead is the switched 12v power wire at the factory amp. Probe each one of the wires until you get 12 to 14 volts dc with the key and radio on, and 0 volts dc with them off.

Firewall?? Power??? The battery is in the trunk.

Thanks for the info. I have a V, battery under the hood.

:(

Thanks for the info. I have a V, battery under the hood.

:(

I am pretty sure the battery is under the hood on all the gen 1 cars. This is the gen 2 forum, though. And wire codes will not transpose.

Just a tip, if you're looking for a little bit more bass, remove the stock sub because it will give the bass an opening into the cabin.

Everyone should do this who have/are going to install a sub in the trunk. The leather back seats muffle the sound of the bass so having a port where the bass can travel cleanly through makes a big difference in the sound quality.

Everyone should do this who have/are going to install a sub in the trunk. The leather back seats muffle the sound of the bass so having a port where the bass can travel cleanly through makes a big difference in the sound quality.

i agree that the big hole theory is good, but i disagree with cleanly passing through. enclosure ports aqe precisely tuned to avoid whistling noises and port turbulence. simply hacking out a 10 inch diameter hole and calling it a port doesnt compute in my book. although, cadillac qut the sub in the rear deck and not the trunk for a reason...