mini cooper, woofer, 6x9’s, components?

Best 8" - 12" woofer?? (combined sq & spl)
Mounting depth: 4"-6" (yes, small!)
Price Limit: $300
Amp: ROCKFORD FOSGATE T400-2
2-Channel 400W rms

I will build enclosure according to sub.

I have 2 boston G5's in right now, too much weight and space...

Also, i need a good set of 6x9's for the back seat, 3.5" mid, and 5.25" components (1" tweet) up front. As well some decent sound dampening for a good value.
Price limit: $350-$400

Anybody have any recommendations?

well....your going to get loads of answers andopinions for the best items. for the depth you have it would be well worth looking into shallow mount subs. i'm currently running a kenwood 10" shallow sub and it work good. and it only needed .6 cu/ft. mtx also makes shallow mount subs and there's a bunch of other companys as well.  as for 6x9's, my personal opinion you dont need the best ones if there going in for your back seat. just get a good quality 3 way and you'll be set, as for the 5.25's i'd look into a set up alpine type r's for those...i like the sound of them. they might push your budget a little but at least you'll have good quality sound depending on how your deck is.

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Tri County KustomZ
certified installer