Been unhappy with my audio at the moment, Deciding to dive into DiY. I don't have much knowledge as I am learning as I look for what I want. I want to have more bass overall (mainly front door bass).

Things I'm wondering:

1. I've heard that sound treatment might help with this. If you also agree, what sound treatment sound I purchase and use? Any techniques?

2. I've seen some people with the Teyes also run a DSP. Is it a noticable difference or worth the extra cost versus using the internal DSP in the Teyes unit?

3. Now this is the "huh" question. Kicker has a shallow 6 3/4 sub that gives a frequency response similar to an 8. I'm wanting to try that for the front doors and see if that completes what I'm missing. So far on paper it looks like it would fit maybe with a new or modified adapter. Or in your opinion would just switching from a coaxial to 6.5 sub in the front be better?

4. I keep noticing people talk about the tweeters. I do notice the feedback coming threw them when no audio is playing or very low. Is it even worth changing? (I do have a dash Matt that covers the fronts anyway)

Just for clarity here's my current setup done via a shop: • Teyes CC3 2k (installed myself) • 4x Kicker 6.5 Coaxials • Kicker shallow 8 rear deck (2nd sub now lol) (Deck is also sound treated and hard mounted no bracket) • Kicker 300w mono amp • Alpine KTA450 45w to the doors

Things to note: • Tweeters still have power and are stock. They do give feedback • This is my daily and I always have a lot of stuff with me. A Ported sub is the very last option for me. Maximum space whenever possible. • The shop at first put in a kicker 8 shallow box to replace the rear deck 8 as they didn't want to touch it. I liked the feeling it gave but I didn't have the sound that having the 8 in the rear deck gave so i "destroyed" the rear deck myself and put the replacement kicker 8 for them to wire. I have the sound I want but for the bass I like distortion become a problem. I blew a 8 within a year of install. On my second 8 now. • I have a few mustangs and I really like the 8s they have in the door because get that bass hit right at my ears and I don't feel like I need to turn up the music with the windows down. Versus right now in the LS where since I'm not feeling as much bass I want to turn it up more.

 

You’re kinda all over the place here. You like the sound it has now but you’re considering swapping the door mids for subs, which would negate the quality you currently have. And you say you like the bass sound you currently have but want to feel it more, and have already blown a sub by cranking it up.
First, mids are very important. Once you only have tweeters and subs you’ll find that out quickly. Possibly swap out the coaxials for components? That should be a slight improvement.
Second, I’m not familiar with a Mustang sound system but in general doors are awful enclosures for a subwoofer. They aren’t sealed, there’s plenty to rattle, and the volume (of air) is never going to be correct for the sub.
Third, you have a dedicated spot for a subwoofer, make use of it. It’s a free-air setup so you’d either have to find a sub that’s good for that type of mounting or create a box. I have an 8” mounted in a box mounted to the rear deck. The same can be done with one or possibly two 6.5” subs. Since they don’t require much volume (box size) you can still fit your “stuff”. Basically what you have done is taken a sub made for very small enclosures and put it in a massive one, no wonder it’s not performing correctly.

Can’t really help with the other items. Don’t know much about DSPs and such.