Used a 4 channel opti drive amp rated 100x4 going to 2-6.5" and a set of tweeters up front and a set of coaxial 6.x8's in the rear. The subs were 2-15" kicker cvr's in a bandpass being driven by around 1200 watts. I couldn't hear the mids and highs hardly at all if I cranked down on it. The rears were run off the rear 2 channels of the 4 channel amp. The front 4 speakers were run off the front 2 channels. They had their own crossover mounted where a kick panel would be.
What I am saying about the box is that typically you need a pretty good size box to hit lows in a ported box? Those 15's in a bandpass was a big box. The ported subs from 25 years ago where in a box that was 3.5 cuft each. Friends who had some 15's which hit low took up the whole trunk of their cutlass. They generally were some series 1 punch 15's being driven by a punch 150.
My brother had 4-12" JBL GTI subs that handled a 1000 watts rms from the early 90's. He had a opti drive amp on them and the brute force on his mids and highs. Those subs hit extremely low but the box took up every bit of space in the thunderbird supercoup that he had.
Had a 12" JBL GTI with a linear power 5002 bridged mono on it. Did not hit very low in the ported box but could thump. Took up around 3 cu ft of space.
I've never heard a "loud system" before like you see in the videos. Loudest I heard was a system my friend did as he had his own store back then. Had 4-15" kickers in a diamond with the ports coming out right close to your head powered by a PPI pro mos 2300. Had to replace windshield a few times and his door seals would blow out if you had the windows up. It just had around 1200 watts though nothing like the 30,000 watts I read about. I have sat in trucks that had 12-12's and never was impressed at all, even though they claimed 156 db.
I want it to hit and don't really care about having 20,000 watts. I dont' really understand why these systems today need that many watts. If I had trouble breathing on 1200 watts I should meet my maker on 30,000.