okay here is my dream setup!!!
kenwood double din with sat nav
exile xtec65s
zapco dc 750.2 front stage amp/ or audison lrx2.4
xtec 65s rear fill coax converted
zapco dc 750.2 rear fill amp/ or audison lrx2.4
2 jl audio 8w3v3 sub/ or hertz high energy 10" depending on your bass preference
zapco dc750.2 sub amp or ??? sorry I would run nothing but zapco amps. I mea they are tuned via usb port and a lap top. how fn cool is that!!!!

I agree with jstoner; pick a killer front stage and build off that.
There are a few companies who are ahead of the rest as far as front stage such as Hertz (watch for fake product!), Focal, Dynaudio and Rainbow. Look for something with good midbass response.
Don't forget about all the peripherals of an install, primarily sound damping. It will make or break your install if at all SQ based.
My $.02