Over the last few weeks I've been researching audio upgrades for a 2021 Camaro 1SS. For those who don't know, it seems the 1SS in 2021+ does not have the amplifier in the trunk like previous models. It has no amplifier at all, like the 1LE versions. Luckily Gen5DIY sell a breakout harness for non-amplified Camaros. The creation of the harness came from Msquared, who I've been talking to throughout this whole process and has been tremendous help! Here is the link to his thread that basically walks you through the entire process and is extremely helpful:
https://www.camaro6.com/forums/showthread.php?t=583735
He guided me with the speaker and amp purchases. I ended up copying his setup basically. Instead of the AudioFrog GS690 I went with the GS60 per his recommendation as I was going with a subwoofer. I got the KEY200.4 amp for the front stage, leaving the rear speakers on the radio module. I also got the KEY500.1 for the subwoofer, as it's small enough to fit next to the 200.4 in the little foam insert and also has built in auto DSP.
Installation was... not for the faint hearted. It was difficult per say, just very time consuming. I was also applying sound treatment where I could during this install, so I took the entire back end of the car apart, interior wise. From the door jams to the rear trunk lid I removed every single piece of interior. The hardest part is just the lack of room. I'm 6'2" so I can't fit back there to begin with, but then to twist my body in the ways needed to pull the clips out was very difficult. If you were just running the wires from the radio module under the dash to the trunk, you can get away with just removing the back seat and then tucking the wires along the interior side panels. Removing the A Pillar trim was also a bit daunting, as it feels like you're going to break the thing. On the passenger side I did sort of break the clip. The way the clips work is there is a metal clip that essentially digs into the plastic of the trim. However when I pulled that trim piece off, the piece of plastic that sticks out for the metal clip to dig into broke. It stays in place fine enough now that it is back together, but something to be careful of. I'm not sure what I could've done different as the driver side came out fine.
Removing the driver side dash speaker was also a pain, as the one screw is right up against the windshield. With a 7mm box wrench you can probably take it out fairly quick, but I only had 8mm as my smallest box wrench. I instead used a 7mm socket on a swivel extension. It barely fit and as I loosened it got more difficult as there was even less room for the socket to fit. Once you remove the dash speakers it isn't too difficult to install the new ones and run wires to them. If doing a similar setup as Matt and I, and using the biamp feature of the 200.4, you have to run new wires to either the dash or door speakers. Dash speakers are easiest as you don't have to go through the grommets in the door.
Door speakers were easy enough to replace, plenty of resources online for removing the door panel.
The next hardest part for me was removing the "Multi-Use Module Bracket", basically the piece of plastic above the passenger footwell. There are 4 7mm screws that hold it in and the front 2 are easy enough, but the back 2 are difficult as they are so far back and you can't see them at all. So you have to feel around with your socket/extension for them. Removing the passenger seat would probably make it a little easier to lay down on your back in the car and get up in there, and would probably help for working in the back seat area as well. One of the screws fell underneath/behind the carpet when I got it loose so I then had to spend some time trying to pry up the carpet to get the screw back. Once you have that off it isn't too difficult to unplug the X1 plug and plug in the harness. Using a little pick tool helps undo the little tab that needs to be pulled to release the plug. I'd advise you wire the input/output speaker wires to the harness outside of the car, because there is no way you'd be able to connect wires up in the dash where the radio module is at. I prewired the speaker wires to the harness first, ran the speaker wires through the car, and the last thing I did was plug in the harness and button everything up.
Subwoofer was "straight forward" enough. I went with a JL Audio Stealthbox as there was someone in a local Camaro club selling theirs for about 50% off, and a goal of mine was to retain as much trunk space as possible. I followed the directions online, the only issue I had was an extra module in the driver side trunk well that wasn't in the instructions JL Audio has. Luckily one 10mm bolt holds it in place, and there is enough slack on the wire harness that it can be remounted in the "spare tire" trunk cavity.
Wiring power is luckily the easiest part of this job, since the battery is located where the amps are installed. Plenty of grounds to choose from there is an extra terminal on the positive side than you can latch onto for power.
The Kicker KEY amps are nice as they have a built in DSP that automatically set themselves up when playing a couple test tracks. This was crucial for me as I have never tuned a car audio before, but obviously want it to sound good. The 200.4 uses a microphone that you put on top of the driver's head rest. Takes about 5 minutes to setup. You can toggle between the equalization on/off afterwards. I can tell a difference between the two, but to me it doesn't make a huge difference. It obviously does something but I'd listen to it either way. One isn't bad and one isn't good basically, to me they are just different. I've left it on because I figure I might as well use it. I might try the setup again just to see if I get different results. The first time I did it was at about 11pm and I was just anxious to get finished. I then set the gain, which is definitely needed. At first I was a little disappointed because I still had to turn the volume almost to max just to get the loudness I was looking for. After setting the gains though, now I barely have to turn it 1/3 of the way for it to be plenty loud. I may readjust the gains at 0db instead of -5db as right now its plenty loud, and I think I'd rather sacrifice some loudness to get more clarity and less clipping.
For the KEY500.1 there is no microphone, but you play test tracks and set the gain and then play a sweep and the amp will calculate the low frequency. Took only about 2 minutes and from what I can tell it seems to have worked properly. Now when I play music I can actually feel some of the bass in me, whereas without it to me there is essentially no bass at all. I think there is still some fine tuning I need to do, but the system has improved greatly with these upgrades.
I do have some weird glitches, like the turn signal chime is only playing through the rear speakers now. Which I don't see why they would, since the "door open" chime plays through the front speakers (pretty loud now I might add). Not a big deal just odd. I also get a quick "pop" or clipping sound when I unlock the vehicle or open the trunk. Something to do with the electronics turning on. I only noticed it after turning up the gains, which makes me want to readjust them to be a bit lower. Something I'll have to look into over the weekend. Overall this project took roughly 35 hours over the course of 5 days. I basically removed every piece of interior besides the main dash, front seats, center console and carpet. Luckily now I have a base to start from. I could more easily add different amps, even a dedicated DSP.
I'd take a picture of where I have the amps but the Stealthbox prevents me from easily flipping up the trunk floor piece, and I have my work gear in the back that I don't feel like taking out at the moment, so I'll post one another time. Basically I have both amps side by side in that foam piece that supports the trunk floor and holds the tow hook.