GT2 Subwoofer Upgrade. 8" ported sub install with pictures and basic guide.

Theemfinger

Member
54
25
18
USA
Recently bought a Stinger GT2 with Harmon Kardon audio system. It sounds great but lower bass is lacking in my opinion, so I decided to try and fix it. My last car was a 08 G35 with the Bose studio on wheels or whatever they wanted to call it. You can say what you will on Bose, but it had 10"s in the doors and a 10" sub in the rear deck and had solid bass for a factory system. With how easy it is to access the battery and factory amp, i decided I was going to try and add a small sub to the hatch. So for this one i tried to keep it simple and not get too crazy. I hope these pictures can help someone if they are confused about installing or scared of installing. The install is super simple on this car since the battery in in the rear under the tire and the HK amp in in the passenger hatch side panel. I'd also like to thank WildBill on here for providing some solid pics to help me plan to do this install.

First the car. Stinger GT2 RWD. Only things i have done so far are ceramic tint and rear stinger badge.



Now for my system, I wanted something small, but with good low end. I've always liked ported, so I decided to stick with what I know. I wanted as small box as i could while still being able to hit the lower notes. I've also like smaller internet sub brands, and after doing some research I eventually settled on the sundown SA8 v3 sub, which is somehow tiny and massive at the same time. I wanted to keep it lower power so decided to stay around 500rms and went with a basic rockford fosgate amp with an Audiocontrol LC2i for LOC duties. I also picked up the remote bass knob for the LC2i and an aero port for the box.







Things you will need.
1. An Amp. Something 300-800rms is plenty for this car. Don't get a cheap brand here like boss or pyle. Don't look at peak power. I recommend something fairly small too so that it is easy to mount.
2. A sub. Personal preference. Size, loudness, music choices, etc. Don't expect magic from super thing tiny sealed subs.
3. Wire Kit - I built my own 8ga kit from KnuKoncepts with a fuse block, 5ft high end 8ga pwr/3 ft ground, sub speaker wire, LOC speaker wire, remote wire, terminals. You can get all in one kits, but I wanted high end flexible OFC wire and didnt want to pay the higher price for 20ft kits when we only need a few feet.
4. If your amp doesn't have high level inputs, you will need a line out converter. The Audiocontrol LC2i is a solid choice that offers neat features to clean the factory signal up. Basic ones are like $10, lc2i is ~$100. It also has a nicer bass knob to control level that allows you to flush mount for a cleaner install.
5. A basic knowledge of 12V electronics do's and dont's. It is fairly straight forward, but knowing how to crimp terminals, proper fusing, grounds, etc. Nothing crazy. You can't really hurt yourself, but not properly fusing a wire that can short could start a fire, and thats no bueno.
6. Wire cutters/ wire crimpers/ random connectors/electrical tape/zip ties/etc.

Bringing the car into the garage to begin the operation.



It took me a few hours because i was trying to find tools and had to make a trip to the hardware store, but everything came together great. To start, you need to tap into the factory amp. You can take the side panels off if you wish, but i was lazy and decided to access the harness from the fuse access panel. Just unclip the harness and pull them both out. Find the correct pin for what you want to tap in to using the pin diagram below. I used the two subs and also the ACC wire for a remote) (Note: It does not seem to roll off the frequency from my limited testing. I was concerned the bass would be filtered below 50Hz or so, but it still sounds fine in the low 30s. Because of this i would recommend the sub output be used for the LOC. I will test this a bit more with time.)The subs are on the red connector and the ACC wire is on the blue one. I used quick splice connectors to keep from messing the harness up too bad. Just put the wire in the connector and use a pair of pliers to clamp it down. After this, you need to run wires down to where the LOC/amp will be located. I used some 16ga speaker wire and ran it down and out of the way. I also added a switch to the remote wire to allow me to turn the amp off if I take the sub off. Its tucked behind the fuse box access panel.











Next, tap into power at the battery and ground on the frame where the battery is grounded. Make sure the power wire is fused properly with the required fuse size. leave the fuse out for now. Route these to where the amp will go. Connect these to the amp and also connect the remote wire you ran earlier. If you run an active LOC, you need power/remote for it. I grabbed power at the amp using smaller red and black wires and included a smaller 5A fuse inline to be safe. Connect these to the LOC along with the factory speaker wires.





Now this is where I like to test the equipment before I spend a bunch of time cleaning the install up. Luckily it worked perfectly the first time.



Now that I know it works, it needs to be cleaned and finalized. I made some amp racks and trimmed them to fit under the spare tire. I carpeted them and mounted the equipment to them. I also bought some metal bracket from the store and mounted them to the studs already in the car not being used. These are M6 bolts, so you just need m6 nuts and some kind of metal bracket. Both available at lowes or home depot. I used a bracket that i cut down to size, bent, and then mounted to the amp boards. I used a socket wrench to tighten these to the studs on the car frame. Everything fits perfectly under the tire. I wouldn't want to go much bigger on amp size or else you will have to work a bit harder to mount it. Speaker wire is ran around and pops out near the sub so you don't see it except for a small piece if you are looking. I have extra wire tucked behind the sub so you can move the it into the back seat or take it out easily if you need room. I zip tied everything so that it looks nice and nothing would move around. It looks fairly clean in person, but the photo with shadows looks ehh. The top down photo includes the bass knob wire ran down the driver side and hidden, with speaker wires hidden on passenger side.







I installed the bass knob in the front fuse panel cover. Its a cheap part thats easy to access and replace for ~$10 and puts the knob in a decent spot to adjust. I didn't want to drill into any major piece of the center console or dash, because that just seems rude to the car. The wire is hidden and ran along the driver side and then pops out in the rear hatch and connects to the LC2i.



I built the box last weekend based of the recommended specs and trying to not use too much of the rear space. The box is 0.75 cu ft tuned to 34hz with an aero port. The front is double baffled to flush mount the sub with internal bracing. I went with black carpet to match the black interior. The box also has a binding post terminal to easily unhook the subs if i need to take them out.





Box Installed. Its pretty small in person. Yes it takes up room, but not too much, and it can be easily turned or moved to fold the seats down. For me, its out of the way 90% of the time I use the hatch. I am working ideas to keep the sub secured. I will probably be using the anchors in the back of the seat, just need to figure out the best way.



It sounds great. I live in a neighborhood so I have not tested it extensively, but it is impressive on my drive to dinner tonight. You wouldn't know it was an 8" sub if you didn't see it. i still need to mess with the LC2i a bit as i didn't have time to get it correctly dialed in. If you are looking for an increase in bass, don't hesitate to look in to adding a small sub to the hatch. You can do it for fairly cheap if thats what you desire.

Let me know if you have any questions. I can take more pictures or offer better explanations if needed. I treated this as a fun mod to the car and I am super happy with the outcome. Thanks for looking!
 
Last edited:

Menissalt

Active Member
139
28
28
North Texas
This is a great write up. While looking around for accessory ideas I noticed the battery and fuse box and got excited by how easy it would be to install an amp but didn't know the factory amp was also back there.

I'm going to wait until I can get a JL 10w7ae before I do the install but I'll be referring back here when I do :)
 

Theemfinger

Member
54
25
18
USA
Can I ask where you find the wire diagram? Is it comprehensive enough for a remote start install?
I found it on this site somewhere. It was just for the amplifier pinout. The information you are looking for exists, just need someone who can access it.
 

Kamauxx

2500 Posts Club!
4,558
1,678
118
Have you considered velcro strips under the box to secure it to the carpet?
 

FokalPoint

Member
98
83
18
Have you considered velcro strips under the box to secure it to the carpet?
I've done this on past builds and it works great. Definitely recommend considering it.
 

Kamauxx

2500 Posts Club!
4,558
1,678
118
I've had mine velcro'd to the back of the rear seats for almost a year and it's still holding up great.
 

Tweakin

New Member
1
0
1
How did you set your LoC? I have a LC7i that im going to use, but i dont want to mess up the factory speakers turning the volume to set the distortion levels
______________________________
 

Theemfinger

Member
54
25
18
USA
I set it to blend in well with a max volume of like 25 on the headunit and bass at +1. I don’t know the best way to do it with the various adjustments on my LOC, but it’s been working well. I also have the adjustment knob ran up front so I’m always adjusting it depending on what I’m listening to.
 

KLR STINGER

Stinger Enthusiast
512
367
68
How did you set your LoC? I have a LC7i that im going to use, but i dont want to mess up the factory speakers turning the volume to set the distortion levels
I am using Lc7i as well. Just set you main volume to your max listening level, and set your channel gains, and accubass levels until the Maximized LED blips and then back off. Then set your amp gains to you desired level ( or if your amp has clip led, then back off.) Works great in my application and I get solid bass output all the way to max volume, without the drop off of the OEM levels.
 

Aarvix

Active Member
362
160
43
North TX
Great write up, thanks for taking the time to make it!

Sundown makes fantastic subwoofers, I have an SA-12 in my truck.

Stinger definitely needs some real subs, not those turds under the seats.
 

Beazy81

Newish Member
5
10
3
Very informative post. Great job on the install. Couple quick questions, first, as far as grounding the amp to the same spot the battery is grounded isn't there a chance of ground loop issues or noise? And second, how much space does your port have to breathe or do you have it almost against the side panel? Thanks for your time, not criticising just curious.
 

Theemfinger

Member
54
25
18
USA
Very informative post. Great job on the install. Couple quick questions, first, as far as grounding the amp to the same spot the battery is grounded isn't there a chance of ground loop issues or noise? And second, how much space does your port have to breathe or do you have it almost against the side panel? Thanks for your time, not criticising just curious.
I’d say it’s 3-4” on each side Of the box. It’s plenty of room for the port. I took a quick picture, but ignore the dirt. I had my mountain bike in the back.

As for the ground loop, I have never heard of that issue. The negative terminal of the battery completes the circuit and it’s where all grounds go back to. It should be the ideal spot for the ground wire. Ground loop noise usually comes when one device has a bad ground, and you would hope the factory devices have good grounds.

______________________________
 
Last edited:

Beazy81

Newish Member
5
10
3
Thanks for the response. I agree with both points. After I thought about my ground comment a little more I realized it was a foolish one. Lol. Not sure what route I'm going with mine yet but I collect old school Rockford Fosgate and I'm thinking about doing a custom sealed fiberglass enclosure with floating amp rack. Got 2 punch 40 amps and a pair of dvc 10's I think will get the job more than done.
 

mfenske

Member
57
20
8
Portland, OR
Thanks for the response. I agree with both points. After I thought about my ground comment a little more I realized it was a foolish one. Lol. Not sure what route I'm going with mine yet but I collect old school Rockford Fosgate and I'm thinking about doing a custom sealed fiberglass enclosure with floating amp rack. Got 2 punch 40 amps and a pair of dvc 10's I think will get the job more than done.
Old School RF FTW!!!!
 
Top