[BR3W CITY]

A grand is doable for a "Clean" system, but you won't be setting DB or SPL records.

There are a few ways you can do this, so I'll pose them seperately.

1. BASIC
Buy a good HU with good power output (over 30w per channel)
Buy a single 10" sub in the 250-500w range
Buy a matching mono amp
Buy a pair of 2 or three ways for the doors (make the doors the "rear")
Buy a pair of small speaks for the dash (making them the front)
OR
Buy a speaker box/corner box and get speakers for a rear-fill. (thereby making the doors the "front", or by removing the doors and having the dash speakers and rear fill)

This is probably the cheapest way, and gives you better speakers, a better/cleaner sound source, and a sub. This will have the least real "power" in the speakers, but will still be much better than stock. You will also have good "boom", but may drown the high-end frequencies at highway speed between exhaust/wind/engine/and sub. The lack of amp'd power to the speakers is often the cause.

2. ENTRY LEVEL

Buy a decent HU, but focus on features you like and don't worry about the power it makes. Make sure it has 3 pairs RCA outputs. A unit with less can work but indicates a lower end unit not designed for "full" use.

Buy a pair of true Component speakers for "front" (doors or dash)
Buy a pair of decent 2 or 3 way speakers for a rear fill
Buy a single 8-10" sub
Buy a 3 channel amp OR a small (~100w) stereo amp and a mono amp for the sub.

In this way, you would run the components amp'd, and the regular speakers off of the HU. The 3 channl config would include the sub making the wiring simple, and not needing a second amp, but 3 channels aren't as common and sometimes are more expensive that 2 seperate amps. You get better audio from the components, but the NEED for an amp becomes apparent. Running components without an amp can sometimes sound worse than running a regular speaker the same way. You save $ by not buying expensive components an another amp (or larger amp) for the rear speakers, but lose power and sound quality. This is acceptable to some folks since the rears are fill-only, and the front components handle most of the SQ.

You can also do a variation of this by swapping the components and isntead running TWO pairs of good 2/3 way speakers, and pairing them off the stereo amp. This will lose F/R control, but will get 4 speakers amplified cheaply as long as the power and resistance divides out. This isn't ideal, but has been done.

3. INTERMEDIATE

Same as above, BUT
Buy TWO pairs of good 2 or 3 way speakers
Buy a 4 channel amp*
Buy a mono amp for sub*

*or buy a 5 channel amp
This retains L/R/F/R controls, and allows for full power to each piece. This is a pretty good "regular" way to add speakers and a sub. It delivers enough power to each speaker, will sound much clearer than non-amp'd speakers. 5 channel amps can be a bit expensive sometimes, but you can always get a good 4 channel and speakers, and add another amp and sub at a later time.

4. ADVANCED

Same as above, BUT

Replace one or both of the regular speaker pairs with Components (the real ones with external crossovers).

Increase the amp size to support the higher power ratings on the crossover speakers, and consider 2-amp method, seperating the sub to a mono block or its own stereo amp.

This will also allow you to do a better job sizing the sub-amp combo, since you can go MUCH bigger on a mono than on a 5 channel.


5. OPTIONAL

Two pairs of good components
Two stereo amps, one for each component pair
Mono block amp or Stereo amp
Single 10-12 sub or pair of subs
Get it all from a company like Alpine, and use their staging device for an attempt at sound staging your car.

This stuff is all pretty much costly and not gonna happen under $1k, but I wanted to illustrate some of the "tiers" of equipment.