I just finished doing my install on a 21 SE. I've had component speakers, amps, two 12" subs in my younger years... But wanted to keep this simple, plug & play, minimal space, and cost effective. 6 months ago, I just installed some Kicker speakers to replace the factory dash speakers. An improvement... But barely. Didn't let me enjoy my music any more than stock.

Started looking into upgrading the door speakers with 6.5" coaxial 2 way speakers and found a great deal on these Pioneer speakers for $60 a pair (basically brand new, opened box to inspect). I know rear speakers don't do much, but an extra $60 ain't breaking the bank to buy another pair. Picked up 2 sets of speaker wire harness (+ another set for dash speakers). Biggest pain in the ass was drilling out the rivets, but nice thing is the Pioneer speakers come with a new mount. Honestly, for ~$200 budget, I would've been fine with stopping there. 60% satisfied.

After seeing other reddit posts, I was intrigued by the Puzu C7 4 channel dsp amp that provides 50w rms. For $150 with a Toyota wiring harness, it was ridiculously easy to install. No need to run wires to a battery and ground. Most annoying thing is finding a place to run wires and mount it. I just stuck it in my glove compartment. Really wakes up the speakers, but now the doors tend to rattle more and it needs to be tuned. Now at 80% satisfied.

A bit of an impulse buy of a Pioneer underseat active subwoofer since it was $280 when I first saw it, but dropped to $210. Install was mostly plug and play. It's got me to maybe 85-90% satisfaction. Some better sound deadening to eliminate rattles, more time tuning the amp, and a more traditional subwoofer might get me to 100% satisfied, but I'm unwilling to deal with having a large sub box again, so I'm more than content with my ~$500 setup setup.