It does sound better than the stock system. However, if you replace the spakers on the stock system and toss the paper cone junk they put in at the factory, the stock system will sound much better than the HK. As well, the HK is much more difficult to upgrade. You pretty much have to bypass the whole stereo system, run it through a sound processor, then to n amp and then to the speakers.The regular 6-speaker is more than adequate. Never have or never would go HK. You'll be more than happy with your choice.
If you are never going to upgrade either one, should have gotten the HK. It does sond better. My advise, change the speakers and put in a stealth box in the trunk and call it a day.