Improving the stock audio system on a 2012 DCSB

Hi Folks, Sorry for the noob questions. I've never been good at car audio stuff so I'm hoping your guy's expertise can help.

I'm a little underwhelmed by the sound quality of my Tacoma's radio and occasionally go through some major buyers remorse for not ponying up the cash for the JBL audio package. The other 2 Toyota's in my household have the JBL and its really quite good for a factory upgrade.

Anyways, I'd like to get a bit more sound and being that I'm good with home audio, I understand better speakers will help but not without a headunit capable of driving them properly. The bass overall is also lacking for my liking.

The problem is I dont like the look of non OEM stereo's and I enjoy having the bluetooth and the ipod integration and the USB and steering wheel controls and all that. Given all of that I'm hoping some of you folks who are knowledgeable when it comes to car audio can guide me.

How do I keep the OEM radio and get better quality sound? Is there a way to improve the bass output along with the rest of the audio without a sub?

What are my options when it comes to boxes for subs? I havent found any good small ones. that fit behind the seat. Is it bothersome to passengers to be sitting on or with their back leaning on an active subwoofer? Passenger comfort in the rear seats is important because I use the truck for long distance drives like road trips.

 

The only thing that I found that looks like it really works is helix. It's German stuff imported by Rockford Fosgate. they have a harness for Toyota that is 100 percent plug in play. the big problem is you can only buy it at Crutchfield for 100 percent MSRP. Another option might be purchasing the harness from helix and using any hi input amplifier. I was hoping someone might be able to verify this.