Re: Full system advice for a newb??
I would look at Memphis mclass for nice speakers for decent price put some 6.5 components in the front and some 6.5 coax in the back it'll cost about 400 but they are really nice and very well built. Depending on budget though I would go with incriminator a speakers if I only had 250 to spend.
Amps vary old school is usually cheap and still very nice but they had there issues here and there. American bass makes some nice budget amps as does ppi jbl is also great
Depending on what substage you want later it may be a too idea to get a 5 channel amp like the alpine pdx-v9 or jl hd900/5 or Rockford p1000x5 or jbl 5ez even kicker has a nice 5 channel. But you usually are constricted to 500w for subs
Far as headunits go pioneer is the cheapest for a quality unity but alpine and kenwood are also good clarion and jvc are ok as well
Like zako said you really don't get much tuning features with a double din so dsp has to be external but for casual listeners dsp isn't a must have either.
A good budget can help us narrow suggestions down for u
2012 Nissan Versa Hatch
in need of everything cept deadener ive got that done