Audio Systems: Car Sound System, dual voice coil, watts rms


Question
Hey im just about to finalise a purchase on my first car audio system i was just wondering if this is a good set up for my 93 lancer and where i could improve it?      
Kenwood KFC-W3012 12" Subwoofer - Dual Voice Coil,
Kenwood KFC-M6952A 6x9" Car Speakers,
Kenwood KFC-M1642A 6" Car Speakers,
Kenwood KDC-MP543U USB Car CD MP3 Tuner,
Kenwood KAC-8104D Car Amplifier.

Answer
You have to start somewhere, Darren. Kenwood is a reputable manufacturer and though [over the years] I have learned that 'one name' stereo systems are not my 1st choice, they can work well in most cases.
It is rare to never that you would see a concert PA which is made up of one brand name (an obvious precision engineered, professional and mobile audio system). It is not uncommon to see live shows with dozens of brand names making up the audio system... Food for thought and with that in mind,  of course their main key IS a professionally designed and operated audio system.
Based on the brand name you chose, I presume you are not expecting this thing the drive nails but if you are also expecting pretty smooth sound leaning towards proper tonal balance while having one brand name to stand behind it, I think your choice is a great 'stage 1' and it could serve you for many years if the enclosure is designed well and the system is setup properly. Certainly, it would be a worthy platform from which to upgrade and build upon, over time.

I must point out a few things:

We only want to consider RMS wattages. RMS (root mean square) means 'continuous' or 'average' wattage in the audio industry.
Manufacturer 'peak' wattage ratings are for one thing.. making money.
If you really feel compelled to know the peak rating, simply multiply the 'true' RMS rating by 1.414.

The KFC-W3012 12" subwoofer actually features a SINGLE 4-ohm voice coil, handling up to 400 watts RMS." It is a decent choice to go with the the amp.
The amp will then deliver 300 watts RMS to that 4-ohm load in mono.
The amp is rated at 40 amps so be sure your charging system (especially the alternator) can handle the extra load (unless the amplifier accidentally shorts to ground it should never pull the full 40 amperes once the amp is setup properly, but we do not want any untimely fires).
While I am on about more power... you really should consider a 4 channel amp to drive the (front) four satellite speakers. The deck has maybe 20 watts of clean power which is great if you never roll the windows down while driving down a road. What I am saying is that that in the real world I do not think 20 watts per speaker is enough to overcome the normal, ambient noises associated with mobile audio.
Another issue is that will have trouble setting the subwoofers' amp up to RMS power ratings with with only 20 per up front.
Since you need to tune the final 'mix' (relative level of subs and satts) to the weakest link, unless you want it to be a bass wagon you will need more power up front.
See... I am trying to help you avoid a situation where you would run out of clean satellite sound long before you ran out of volume knob at the deck... eg "gee the bass works perfectly all the way up like it should, but the fronts are clipping horribly"   ect.
Expect the aforementioned situation if you do not get a real four-channel amp to drive those speakers with.
*The front speakers you have chosen only handle 35 watts RMS so if you ARE going to get the 4x50 watt amp you might want to search for a pair which can take 50 RMS.
IF that ends up being the case, you may want to get a deck which has 3 sets of line-level RCA's output jacks on it. This would allow you to tweak the front to rear fading on the fly from the deck.
You can still setup a relative, overall front to rear on less available pre-outs but it must be set from the amplifier trim pots.

lol  are you still with me?

A dedicated 4 channel amp with 50 watts will give you at least twice the headroom before clipping occurs over using 'headunit power amps'. With crossovers set correctly it is not uncommon to get even more.

once ya go this far.. to ease things tremendously you should consider an all in one 5 channel amplifier to run all of this.
Five amplifier channels, one case, built in crossovers, one power wire.
Here is one I would suggest looking at since you are still having cash in hand:
http://cgi.ebay.com/NEW-KICKER-ZX700-5-700-WATT-5-CHANNEL-CAR-AMP-08ZX7005_W0QQi...
I have seen factory refurbished, re-warranted ones for 179.00 on Ebay.

The price is higher but you get everything in one simple package for amplification and signal processing.
That kicker amp WILL drive nails.

In short, your list will work if you are not looking into high fidelity throughout the entire volume range.
If you want a simple effective audio solution, it could be perfect.

Best of luck and let me know if you need further assistance.

JM