6X9s in the rear?
 

My idea: Put 6X9s (ea in their own box) in the rear area infront of the silver brace. Already have Alpine CDA9886 HU w/KTP mini amp (45RMS X4), and Infinity 6022i's in the doors. If I do this, should I get a separate amp for the rears, or will the KTP be enough? I'm not looking for a boomer car. I Appreciate any suggestions.

My suggestion do not do it. Use the money for a sub and amp. Or a good set of front speakers.

I've done it before in the 350Z mainly because the 6x9s were for a different car before making the final decision with the Z. Now I'm perfectly happy with a 2.1 setup.

2.1 Set up?
 

I don't know what you mean by 2.1 set up.

Meaning a set of components in the front a the .1 is a sub.

Rhinetom the 2.1 is 2 channel (stereo) and subwoofer. The .1 in any audio configuration is the low frequency channel.

I agree with Big on this one, don't do it.

No offense but 6X9s in boxes is a ghetto setup that you would expect to find in an 82 Monte Carlo, not brand new Z.

At least at a minimum get a decent set of components and intall them in the stock location with a modest amplifier.

^This

Yup... unless you spend more time watching movies than listening to music, you're better off investing in a nice set of 6.5" components and taking the time to get the front speakers installed well. I didn't spend more than $250 with my Diamond components.

Plus, you'll need to drive it with a separate amplifier (I'm running 100Wx2 with my front components). The power from the head unit is not enough to drive these speakers to the fullest (i.e., sounds very muddy with inadequate amplifier power). It's not about loudness, but clean power and sound.