Here is a video of my selfmade GFRP enclosure and installation of an aftermarked amp. Make sure you turn on the subtitles. There is everything described. the components costs like 430€ thats approx. $510. The amp and wiring took me 4 hours. the enclosure one day.
Nicely done, might have inspired me to move forward and finish my project! BTW, was the soldered wire to the from passenger speaker to pull a signal to convert for an RCA to the amp? Nice trick on measuring the impedance, hadn't thought of that before!
The amp got a hi level imput (directly from the speaker) with auto sense. so there is no need for a RCA converter nor remote signal. finish your sound project. it worth it!
Thought that was the case, at first I thought you were tapping it to power new front speakers then it dawned on me what you were doing I was like ummm why you dual feeding your doors....duh. Yeah, I will have dual subs in the rear like you did for each side, I have the initial fiberglass shell but need to add additional layers for strength. How many layers did you do on yours? Also how did you secure the box after it was installed? I will also be replacing the door speakers, plus adding a mid and tweeter to the A pillars in the front. 4 amps total, with a mosconi DSP, all active setup.