I'll try to keep this short as possible since could write novels about 12V sound systems and it's a topic I enjoy. Having been a competition audio guy/installer (paid my way through college!) I hope I can provide some assistance below.
Let me first say "audio" is very subjective for everyone. Opinions will ALWAYS vary.
I'll put together some suggestions for a setup trying to keep costs low but value and sound quality high. Here's where i'm headed with my setup. p.s. I listen to all types of music from rock -> hip pop -> jazz -> NPR
1. Front Speaker Mounting - purchase custom kick panels. maybe something like this
. with this option you're not cutting anything original and you can remove it later. also, kick panels are fairly easy to make if you're handy with fiberglass, wood, cloth, and some backstraps. q-logic may also make some kick panes - not too sure.
Cost: Not sure from $30 to $120 is my guess... need to do my own research too
2. Front Speakers - if you're concerned about sound staging then you'll want separately mounted tweeters and mount them as far from your ear as possible and closest towards the front. i don't personally think staging is all that important so i'm going to mount my tweeters in the kick panels as well. i don't want to drill holes in my doors or door panels.
separates or components? the sound variance at cruising speeds is negligible to me. at competition sound levels - HUGE difference.
Cost: Craigslist! $100 est.
3. Rear Speakers - Unlike others, I like 6x9's. They're sorta the red headed step child i've noticed in the industry. Whatever, I like them because they're cheap and they provide full bass. I'm not looking to get quality reproduction of Whitney Houston's voice from those puppies - that's what the front speakers are for. Get a two-way or separates. The 3-way or 4-way junk that's out there are gimicks imho. They tend to be much too bright sounding. You can also choose to go with a 6.5" in the back also. Have them back-mounted under the tray and the sound come through carpet or the perforated vinyl for a stealth install. You don't want to hear too much highs coming from the back anyway (at least I don't).
Cost: Don't know, I haven't shopped around for 6x9's in a while
4. Subwoofer - I personally feel a subwoofer completes the system. You don't know what you're missing until you've had a car with one. I'm not talking jumping pennies on your trunk lid, just enjoyable and full sound. If the 6x9's aren't enough for you test out 1 8" sub. I went with JL in my day. JL was moderately priced, very accurate, and very efficient with power/wattage. I would go with 2 8"s myself but I only have 2 10" or 1 12" sitting in my garage. I may end up going with 1 10" in a sealed .5 cubic ft box. It should keep the boomy-ness to a minimum and still be accurate.
Cost: I've seen these go as cheap as $50 each in the recycler or craigslist.
5. Amplifier - 30W RMS each speaker is probably all you need to power the inside 4 corners. As long as your speakers are relatively efficient you'll have plenty of distortion free volume. You can choose to power the inside speakers with the headunit but the distortion will kill your speakers at high volume. (Even if you don't hear it, they are probably distorting and your voice coils will die a quick death). If you plan to go with a subwoofer and if you plan to use a Bazooka or a JL, both relatively efficient, then you can budget for 50-100watts of RMS power to each woofer. This has to be clean power from good amps. Not the 1000watt gimicks you see on swap meet brands.
Now onto the subject of # of channels... With my last humble competition level setup, at the time, I went with a good 4 way 100w X 4 channel amplifier powering 12 speakers (3 way separates in front, 6.5" separates in back, and two JL W0 10"). All interior cabin speakers ran off of two channels and the other two channels were bridged to power the subs. It sounded awesome. My point is... this effectively made for a budget 3-channel setup. I spent my money on quality components, and gave up some flexibility with the # of channels. If you decide to go this route, you save money by only having to buy 1 amp (in most cases as some choose to run a dedicated sub amp) and is less installation hassle by only wiring up 1 amp. Just make sure you purchase a good amp and it is 1-2ohm stable. I had a mcIntosh. hehekekeke. I miss that bad boy so much!
you lose front to back fader with this setup but I don't know too many guys messing with their center balance or fader anyway. I normally just use an in-line resistor to attenuate the rear speakers to my desired staging. If you really want front/rear fading capability then you will lose stereo left/right. Normally, 99% of the people going this route chooses the stereo left/right option. On drawback, you'll need passive crossovers to manage the crossover points in this setup. You won't have much flexibility if you decide to add an electronic crossover later on. Again, this is a budget setup and you'll have to compromise.
Cost: $100 (if you're lucky on Craigslist), $250 and up if you buy brand new.
6. Head unit - Plug for my buddy Steve Brown at Alpine! I still think they make the best headunits so I'm biased. I will probably end up mounting my headunit where most people mount the 3 gauges, under the dash. I want a radio delete plate or perhaps i'll relocate the gauges up top. Anyway, radio low level signal makes or breaks a system. Garbage in, Garbage Out. Any modern headunits will produce quality source signal. Start with Alpine then work your way down to Pioneer, Kenwood, Sony, etc.
Stick with decent quality products for the solid state devices (amps, headunits, crossovers, etc). Alpine, Pioneer, Kenwood, Clarion, or Sony - in ranked order. I would not waste your money on JVC, Jensen or the other Pep Boys brands. Unless you want your car to sound how it really soundeed in the 60's. Ok i'm kidding but usually it's not worth the 25-35% you're saving. You have more selections with speaker brands. I guess what I should have asked you is how much you're willing to spend.
Once I get my 200-4R Tranny installed and I rig up a decent security system next will come my stereo setup. Luckily I have spare parts enough for 3 cars probably. I'll have to see what fits best where. I'll update my sig once I get that done so maybe you guys can see what you don't_want/want in your own setup.
Hope this helps!
UPDATE: I found this pic of Robert's install. See custom kick panels and radio install. Even this is much too overboard for my purposes but he did a clean install. :thumbsup: