Your choice of a sub is not really a sub, it's mix of a sub and woofer. If you put it in the trunk, the higher frequencies, like from 200 - 1000 may not come to you, or they will be soft. All this will do is create noise and distortions. I suggest you get these components:
Polk Audio DB1040DVC Dual 4 ohms 10" db Series Car Subwoofer
http://www.techronics.com/caraudio_10442_Polk-Audio-DB1040DVC-Dual-4-ohms-10-inch-db-Series-Car-Subwoofer.html
Here is a good sealed enclosure for your sub:
Absolute MSHF-10 Single 10" Sealed MDF Enclosure
http://www.techronics.com/caraudio_14748_Absolute-MSHF-10-Single-10-inch-Sealed-MDF-Enclosure.html
The head unit is good, good features, etc.
Your choice for the amp is off. It does not include a channel to power your sub.
Here is a nice amp I found for you.
Kenwood Excelon X700-5 1200W 5-Channel eXcelon Power Audio Amplifier
You can connect to it front speakers and front tweeters, and rear speakers.
Plus
It gives 300 rms watts of power on channel 5 for your sub.
http://www.techronics.com/caraudio_15345_Kenwood-Excelon-X700-5-1200W-5-Channel-eXcelon-Power-Audio-Amplifier.html
For the front I suggest you get Polk Audio with separate tweeters.
For the rear, I suggest Pioneer series D (only this series sound good from them)
If you don’t want to replace speakers and you don’t want to play music through an amp,
You can stay with your current speakers. I then suggest you get 20-30rms watt tweeters. Connect them to your front speakers in parallel.
In this case you don’t need a 5 channel amp. You only need a 300-500 rms watt 1 channel mono amp
Kenwood X500-1 500W RMS, Monoblock eXcelon Series Digital Power Amp.
http://www.techronics.com/caraudio_15674_Kenwood-X500-1-500W-RMS-Monoblock-eXcelon-Series-Digital-Power-Amp-.html
If you don’t get an amp, at least replace the stock speakers with nice after market speakers. They will play much better than your current stock speakers.
You have a lot to consider. Go for quality, not quantity. You will see that without distortion and noise you get clean brilliant sound, and that with clean sound you don't need much power to enjoy hours and hours of music that will make your soul smile.