How should this sound?

I have a chevy silverado extra cab and was wondering how you guys think this system would sound with the proper install of course.

Mb quart  QSD216 for the front doors.
Jl 450/4 to run them.  Open to cheaper options! (opinions please).

2 IDQ12 v.2's in a sealed enclosure
Jl 500/1 to run them.

How should the  Sq and SPl be in this setup with it all installed properly?

should I buy these subs in 2ohm or 4ohm , they are dual voice coil I believe. Thanks!

Vandals, you want to give your amplifier the highest resistance possible while still achieving the power/volume level you want. Even if an amp can go stable at 1 ohm, it will sound better with lower loads (higher impedances) because of the damping factor. What this means is that the less an amplifier is loaded, the more control over the speaker it has. Because voltage is proportional to impedance, the higher the impedance of the load, the more of the voltage is dissipated in the load instead of in the transistors.       To put it simply, lower impedance = sloppier bass

That having been said, I will list the impedance configurations with 2 speakers for speakers with whole number impedances. Everything below is for 2 identical speakers, so I won't say 2 speakers every time.

SVC, you can get 1/2x or 2x the impedance of a single coil
8 ohm SVC: 4 ohms, 16 ohms
6 ohm SVC: 3 ohms, 12 ohms
4 ohm SVC: 2 ohms, 8 ohms
2 ohm SVC: 1 ohm, 4 ohms
1 ohm SVC: 0.50 ohm, 2 ohms

DVC, you can get 1/4x, 1x, or 4x the impedance of a single coil
8 ohm DVC: 2 ohms, 8 ohms, 32 ohms
6 ohm DVC: 1.5 ohms (this is what I run, on a 1 ohm stable amp), 6 ohms, 24 ohms
4 ohm DVC: 1 ohm,  4 ohms, 16 ohms
2 ohm DVC: 0.50 ohm, 2 ohms, 8 ohms
1 ohm DVC: 0.25 ohm, 1 ohm, 4 ohms

QVC, you can get 1/8x, 1/2x, 2x or 8x the impedance of a single coil
8 ohm QVC: 1 ohm, 4 ohms, 16 ohms, 64 ohms
6 ohm QVC: 0.75 ohm, 3 ohms, 12 ohms, 48 ohms
4 ohm QVC: 0.50 ohm, 2 ohms, 8 ohms, 32 ohms
2 ohm QVC: 0.25 ohm, 1 ohm, 4 ohms, 16 ohms
1 ohm QVC: 0.125 ohm, 0.50 ohm, 2 ohms, 8 ohms

In a bridged amplifier, your maximum load is (Max load for a single channel) * (Number of channels you bridge), so if you bridge 2 channels on a 2 ohm stable amp, you can only go to 4 ohms. If you bridge all 4 (your amp SHOULD be able to do this if you can bridge 2, as bridging just means putting the amplifiers in series) then you can do 8 ohms. Either way (2 channels by bridging in 2 groups of 2, or 1 channel bridging all 4), you're going to want to pick the same impedance. (I had said 8 ohms before I edited, but disregard that if you saw it, I had a brain fart when I said that)

Oh, I just noticed that you listed a 4 channel and a 1 channel amplifier. Forget what I said about bridging, then. It is true, but doesn't apply with the 1 channel.

Just pick anything above that comes out to an impedance greater than or equal to what the amp will handle. The lower the impedance, the more volume, but the sloppier it will sound. However, JL amps have pretty high damping factors so it should sound good even if you load it to its max. I believe that amp is 1 ohm stable, so I would probably get a couple of 4 or 6 ohm DVC speakers.

Well, if the amp is good, it doesn't matter if you run it to max load, but for cheaper amps, it may make a difference. As I said, with a brand like JL, it won't matter, because they have a high damping factor to begin with.

As for your component suggestions (and also what your sig says you have), I would have to say that I disagree with all of them. Nakamichi, Eclipse or Alpine deck. Focal, MB Quart, or A/D/S speakers. Adire subs. That would make a sweet system.

What kfr01 is referring to is the damping factor of the amp. Now I too have been installing for many many years and long before this class D and mono amp garbage came about. We had class AB amplifiers and some of them were monsters (Alpine 3545 for example). These amplifiers were only stable to 4 ohm mono, thus most of the subs of the era were svc 4 ohm and in some rare cases svc 8 ohm. Now with the plethora of class D amps on the market and their ability to produce gobs of power as the impedence drops, there has to be a tradeoff. This tradeoff comes in numerous forms.

(1) increased current draw

(2) increased heat output

(3) poorer damping factor

The latter part is what I will only touch the surface on. Each time that you drop the impedence by half, so drops the damping factor by half. Down to 1 ohm is far less than running at 4 ohms. The amps damping factor is the ability to control the motion of the driver, hence the sometimes used term, "sloppy bass". If you two amplifiers with the same subs and same box and do a side by side comparison on it, in your car, then you will truly understand the difference. To do a test like this you need a class AB amp (monster 2 channel that bridges to 4 ohm and provides say 1000w rms) and a class D 1 ohm that also produces 1000w rms. The second part of the test is the subs in the box, for the class D amp they need to be wired in a all parallel circuit to provide the 1 ohm to the amp, for the 2 channel change the wiring to a series / parallel circuit to present a 4 ohm load to the 2 channel amp. Listen away to your hearts content after that. Each way has it's advantages  / disadvantages, but in terms of control of the sub or "sloppy bass", the 2 channel Class AB will win every time.