First off, a huge thanks to those who helped me choose the setup and helped teach me how to install. This was my first sub/amp install, and everything went smoothly after a lot of help from some of you. Thanks!

After seven years and 130k miles, the stock JBL sub in my 4runner finally let go. I love some bass with the music, but just clean/audible bass. So, I chose to replace the stock JBL sub instead of just adding another (also didn't want to loose cargo space). I did a lot of searching, and I found several real good threads, but most I found never showed the end result. So, I'm gonna try to sum up my findings and my install in this post, maybe it'll help someone else out.

First up, specs on the stock system. The sub is a 8" JBl with 2 ohm dual voice coils. The amp puts out ~90 watts max, estimated 45 watts rms. The stock sub is ~3" mounting depth.
Second, I chose to replace with JL Audio equipment. I've always heard good things about JL, and after the install I see why, very impressed. I went with a JL 8w1v2 sub (150 watts rms) and J2 250.1 amp (puts out 175 watts rms).
Third, wiring. I tapped into the rear DC outlet for my turn on wire. I tapped into the speaker wires right before entering the sub box and connected to my speaker level inputs on the amp. I cut out a spot on the box and added a speaker terminal plate for easy and quick connection. I did this directly behind the amp, mainly just because it was the only place I had room. I used the bolt for the seat to make the ground. I ran the power wire back, then across the firewall, in through a factory hole. I ran all wires down through the trim, then under the carpet and out in the cutout for the air vent under the passenger front seat.
And fourth, here are a few threads that really helped me out.

EDIT: It looks like the web site I used that showed how to access the sub is no longer working. I do have this process saved in a word file, if you need it PM me your e-mail and I will send it to you. Dannyg did the install and also has a writeup, which can be found here.

JL Audio - Car Audio Systems
And several more that gave me specs on the stock system, don't have links to them.
The end result sounds excellent. It's not gonna shake the car next to you, but it gives some great quality bass that was lacking with the stock sub. Let me know what you think, and just let me know if you have any questions.
Ok, so here are the install pics.
The equipment:

Stock setup:

Sub removed:

Sub comparison:

Modified box for clearance, sub liked about 1/4 inch fitting.

Sub installed:

Wiring:


Finished with amp:

Fuse holder:

Finished sub:

Looks good! Nice clean install. I have a JL 10w3v3 and can say that I'm also very impressed with their subs. Good choice.

excellent! I've been looking/hoping for a thread like this so I too can do this to my 2006 4runner. Awesome.

I think something like this should be stickey'd maybe in the Audio section for future reference.

theres another ground bolt that is better, first u flip the seat and raise the carpet , then u should see a ground bold with 2 wire wires to it, use that insead, and route the ground cable thru the ven cut out on the carpet, each driver and pass side have that same ground bolt, i use that then the seat bolt.its behind the front bracket mounting area, that hump on the back of it.

Was your amp bad and if not,could you have just replaced the old sub with the new sub? I would like a little more base,but don't want to replace the factory amp like you did.

The 4runner's have a 10 speaker JBL system. The amp in the rear compartment is pushing all 10 speakers. After my install, it is still fully functional, except pushing 9 speakers (no sub). The stock sub is 2 ohm DVC at about 45 watts. You can drop in any sub, but it will not perform good with that amount of power. Also, you're sub needs to be under 4" mounting depth, and most 2 ohm DVC subs are more (this type of sub would work best, but won't fit). I doubt that there would be much benefit from just dropping in a sub. It is pretty time consuming getting to the sub. 3/4 of my time was spent getting to the sub and getting the new one mounted up. It took me no time at all to run a few wires for the amp. There is some good reading in this thread, it is the one that made me decide to add the amp. http://www.toyota-4runner.org/audio-...b-4th-gen.html

I have a 06 sr5. Do you know if they already come pre-wired to install a sub in the back?

The SR5's don't come pre-wired. You'd have to run all of the wires for both a sub and the amp. I've got my amp mounted under the driver's seat and the sub in the rear cargo area. It's all running off of the stock head unit.

Ark Swamp rider,let me know when you are coming to St. Louis,I can get you sweet Cards tickets and you can put my sub and amp in for me.I have an 06 Limited.

Hm, no plans to head up that way, will keep that in mind though. Install wasn't too bad, if you want to try it out I'll be glad to help you out along the way. This was my first amp install, and I had no trouble at all. I took it slow and easy, did plenty of studying to know what needed hooked up where, and it was a piece of cake (just time consuming). I'd say I spent about 6 hours, but that was including a few small breaks, plus 4 of those 6 were spent in the dark, so that slowed things down a bit.

do not use seat bolt as ground part, use the bolt under the carpet like i recommend, its much more better and stealth.

Mine is working for now, so that's all that matters at the moment. I will end up re-routing the ground to the spot you mentioned, just not right away (will have to get some more wire).

the way u have it is enough, just cut a small slit in the carpet if its to short, about 2-2.5 feet is perfect.

Nicely done. I believe i just may order that exact setup...

I finally got some fine tuning done, and I'm very pleased. It's not bass you can feel nor bass that will shake the truck, but it mixes in perfectly and isn't overwhelming. I have turned mine up and it'll thump pretty hard, but I typically keep it turned down somewhat. I've ran a single 12" Alpine Type R, 2 10" Kenwoods, and 2 10" JBL subs in the past (previos rides). I liked all of them, but IMO this is a better fit for me. I like the hidden single 8" better than all of the others. Plenty of punch, but no space sacrificed.