Seeking Recommendations To Upgrade 2006 Ford Mustang GT Premium

I have a 2006 Ford Mustang GT Premium coupe that currently has the stock Shaker 500 stereo system in it. The longer I own my car, the more unhappy I am with the Shaker 500, so I ordered a Pioneer Premier AVIC-F90BT. That is most likely the beginning of an upgrade to the entire system. While the Shaker 500 and 1000 are billed by Ford as premium systems, they are not...at least to my ears. I plan on installing the F90BT and checking out how it sounds with the Shaker 500 amps, speakers, and subs, but I doubt I will keep them. I'm hoping I will be surprised and not have to fork out the cash to upgrade the rest of the components.

If things go as I believe they will and I end up wanting to replace the Shaker 500 amps, speakers, and subs, I am looking for recommendations that will sound great with the F90BT. I have been out of the car audio game for awhile and am not familiar with all of the manufacturers and models out there today. It's been over 10 years since I last upgraded a car stereo system, so my knowledge of current products is limited.

I listen mainly to rock and metal. Zeppelin, Hendrix, Sabbath, The Who, Van Halen, KISS, Metallica, etc. I do have a taste for other stuff like Elvis and Harry Connick Jr. My goal with this system is sound quality. On most occassions I do not blare my music, but because of the vehicle (2006 Ford Mustang GT Premium with Roush performance products installed) I do need the stereo system to sound great at volumes high enough for all of the nuances of my music to be heard over the sound of the engine and exhaust. I'm not going to be entering any kind of car audio shows, but in the end I want it to have a lot better sound quality than the Shaker 500. I used to have a great home component system that was my primary system for listening to music. While my 5 year old digs jamming to tunes, my wife doesn't like it so much, so I've downsized that quite a bit. Right now my car is where I listen to the majority of my music and I want that to be high quality.

I haven't taken anything apart yet, but here is what I've gathered through my research as far as the configuration of the stock Shaker 500:

Front upper door panel locations (2 car door) and rear deck are 6x8 2 way with a small woofer and a tweeter built into a 6x8 speaker plate. Front lower panel locations are 8 inch subs. These subs are driven by 2 amps that are in the front kick panels. The Shaker 500 system with the stock head unit produces 500 watts at max power. The head unit also has speed volume adjustment so the volume increases as the vehicle goes faster.

I have been researching the various manufacturers and their products that are out now. I went with the F90BT for my head unit because of the all of the features it included for the price I got it at. I've talked to several local install shops and they are pointing me in different directions, depending on what they carry. Based on the research I have done online by reading reviews and what the components are made out of along with their specs, it looks like JL Audio has some great stuff. I was kind of leaning towards their Evolution C5 or ZR speaker series with their Slash v2 300 or 450 amp.

1. With that said, what are your recommendations?

2. What kind of wattage should I aim for? Like I said earlier, I don't blare my rock and roll, but I do need the new system to be easily heard clearly at lower volume levels with a high sound quality so I can hear it above the engine and exhaust noise I get inside the car.

3. What manufacturers and products do you recommend?

4. Anything I should know about the JL Audio Slash amps and their Evolution C5 and ZR speakers?

5. I'm not sure if higher quality 8 inch subs in the lower door panels would be sufficient to give me what I want, so I might need to spring for 1 or 2 bigger subs and have those mounted in the trunk with a dedicated amp to drive them.

6. Something else I need to be educated on is these D Class amps. I don't remember these being an option when I designed the system in my other vehicle around 10 years ago. I'm a guitarist, so I know that digital amps may sound good in a studio setting if they are tweaked properly, but in the end nothing can top the sound of a good cranked up tube amp pushed into overdrive. Does that same principle hold true for these newer D Class amps versus the AB Class amps?

7. Are there any lesser known manufacturers or brands around that produce products of the same qualities for a cheaper price? I'm prepared to spend up to a couple grand to get what I want, but I know my wife will have a fit, so the cheaper the better. I want a good bang for my buck without sacrificing sound quality.

I am only seeking recommendations to use for informational purposes only. I am going to research any and all recommendations including internet reviews, expert reviews in trade magazines, and going to shops that sell the recommended products to hear how they sound for myself.

Thanks in advance!