So I think I've got things more or less figured out my G35 coupe stereo install. I will stick with the stock headunit for the cosmetics and NAV integration. I have some questions, but first the equipment list (I have only purchased the sub so far):

Sub:
Image Dynamics ID 10 v.3 specs

Amps:
Audison SRX5 (4x50 RMS + 180W @ 4ohms) - specs
Audison SRX1 (1x210 RMS @ 4ohms) - specs

Speakers:
Focal 165CA
Focal 165A
or
JL Audio XR650-CSi
JL Audio XR650-CXi

What do you think? I also have a couple of questions:

1) amps - the single sub can only be run at 4ohms, correct? Do you think the 210W will be enough? Or, do you think the 180W from the 5 channel will be enough (then I only have to buy 1 amp)? The sub says it takes 250W RMS, but it doesn't say at what impedance that is. I want SQ more than SPL, but I don't want muddy bass. Tight, fast hits are what I'm looking for. These subs are reputed to perform well at low power levels, can anyone attest to that?

2) sub box - I'm going to fiberglass a box into the spare tire well. What's the best way to attach the fiberglass bottom to the mdf top?

3) speakers - leaning towards the Focals as they seem to have the best reputation. What do you think of the JL's? I want a warm sound, not too sharp. I'm going to hear them first, but looking for any real world experiences.

4) There is room for a pair of 6x9's in the rear deck. Would it be better to go for those rather than the coaxials in the side panels? There are some Focal 6x9's available. Nobody ever sits in the back seats, so staging is being tuned for the front seats.

 

If you want a warm sound, I think you'll find the Focal's fatiguing over time. I'd look for some DLS or Morel or even a/d/s/ for a warmer sound and a fuller midrange. I think highly of the DLS UP6. Of course, the Iridium sound good too.

No rear speakers, they are a commie plot that endangers America. Spend the money on the best front stage you can get and blow off the rears.

 

I agree about the rear speakers. You don't need them. I'm doing the same as you with sticking with the stock HU and I'm going to disconnect both sets of rear speakers. Like you, no one sits in my back seat so I don't think that I need rear fill.

For a component set, I bought CDT ef-61cfi/24 based on their reputation on Sound Domain. You can get them for $225 delivered from an authorized dealer.

I think that no matter what component set you go with, you're going to want more than 50w RMS/channel. Most of the higher end comps need more power to really come alive.

You should be happy with the ID sub. I bought a 10" IDQ for my system. It's not installed yet though so I can't tell you how it sounds.