what do you mean "not be happy with something not custom"?
I said install, not gear. You said you weren't going to be able to do it, which I assumed meant that you would have to pay someone to do it.
For starters, the XXX mids that you originally talked about must be in an enclosure, that will be total custom work (and will not be cheap). Then, would your friend really want to spend all that money on equipment for it just to amount to nothing more than a box in the trunk and speakers/etc in factory locations, and amps screwed to the back of the seats?? Judging by the way he (or you) are "going all out" on the equipment, he'll probably want some fancy amp racks made, a fancy enclosure (which a "standard" box for 2 subs will probably cost a minimum $200 for a shop to build, and that's at the very cheapest) and possibily even some nice painted 'glass.
So, if you are going to have to pay someone to do the install, draw the line right now before you settle on equipment; Fancy or boring. Because even a "boring" will cost ~$500 for a shop to do if they have to build the box and install video, and a "fancy" will easily cost upwards of $1.5k
$6k on equipment is useless if the install doesn't properly utilize equipment and get the full potential out of the equipment.
Not trying to rain on your parade, just wanted to make sure you didn't overextend yourself on the stereo spending //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif