Here is a custom stereo system for a 2006 Volkswagen Jetta.  I've had a custom stereo system in just about every car I've owned since my youth.  I can honestly say this is one of the most impressive systems I've ever heard.  The stereo is very balanced and so crystal clear that the question becomes how loud your ears can stand it versus how loud the stereo will go. 

The system was designed  to include sirius satellite radio, bluetooth hands free connectivity, with an interior showing no signs of an after market stereo system.  I wanted to be able to return everything to stock easily as I knew there was a good chance I'd be selling the car down the road.  I also wanted to retain the majority of the trunk space for luggage or groceries.   

The installer had 20 years experience and picked the top brand speakers that would fit in the stock speaker locations.   The brands are Focal, MB Quartz, and one pair of kicker speakers.  He custom designed a downward firing subwoofer box w/ an amplifier rack that retains plenty of trunk space.   I paid over $5k for this system including the system components and labor.

The beauty of this system is that all the work has been done so that it can very easily be installed in any Jetta or similar car with very little labor.   Everything is included from the components to the wiring/RCA's so it will be a drop in installation for buyer.  The charge to remove the system and put it back to stock was $85.00. 

The system includes the following:

Below is the subwoofer box out of the car with the Kicker model KX700.5 in the amp rack, which is included with the system.  VERY AWESOME 5 Channel AMPLIFIER!!!!

Below is a photos of the amp with the surround removed. 

Below are photos of the bottom of the box showing the two 10" L7 Subs.  These Subs provide plenty of base - in fact all of the gains on the amp were set in the mid range as everything was capable of being louder than the ears/body could handle at these gain levels...