Well I have had my vette C5 coupe M6 2000 for a little over a year now.
When I first bought it, it was not 24 hours of ownership and I pulled all the crappy Blows radio out. I went with my old system from my sunfire. I had a Sony Head with HD Radio, Sat, Cd, and USB. I had 2 MTX amps(4 sale) a 4 ch for highs and a 2 ch bridged for the subs, I fabbed up my front speaker plate to place my 5.25 JL comp. And JL 6.5 coax in the rear. Subs I was running (2) JL audio 10W0-8 in a sealed box in the center comp.
The system sounded really good and clear(I did have some engine wine) Big 3 fixed that. I was happy but there was always room for improvement.

So over the past month I spent a little more money on the stereo and upgraded. I now have:

Fronts: JL audio XR 6.5 Comp
Rear: JL audio CSI 6.5 coax(they are turned way down)
Subs:2 JL audio 10W3V3 500 watts in a sealed custom box.
Amps: (1) JL audio 300/4 V2 Slash (1) JL 500/1 they are mounted behind the seats
Headunit: still the Sony(thinking Alpine in the future)
Sound Dead: Frost King Mod

I was tuning everything last night after I recieved the subs in the mail yesterday. All I can say is HOLY Crap it sounds amazing. I have a 135 DB meter and it maxed out, before I would be bouncing at like 129 DB. The Subs are so clear, and really hit hard, I have a new respect for JL, I think pairing the JL amps with the Subs and speakers was the way to go. My highs are crisp and clear I can hear things in my music that I have never heard before. I listen mainly to Rock, and Hard Rock but I put in some clasical and that sounded amazing as well. I have not taken it out on the road yet that will be tomorrow. I still have a little tweeking to do with the EQ.
I have been into car stereo's for 16 years and I have to say that this system sounds like one of the best. I need to get a bigger DB meter to know where I am at.
I will post pics soon, I am at work now.
Thank you to all of the forum members for there knowlege I used some really good tips from all of you.