It all depends on what you are going for and the kind of cash you want to throw at it. If you already have the HK system in the car then, you will have to go a high quality to hear the difference.
I tend to like really expensive shit, as I threw about $1,900 at my sub system, but it is the clearest damn thing I have ever heard. The next step is new fronts, with their own amp followed by the rears and an amp. The fronts will be RS Pros, unbelievable, but the speakers and the amp will be about $1,700 for just the fronts. So you can see why a budget is good.
Polks are pretty good I had a set in my past vehicle, but the guys are right when you upgrade to aftermarket speakers they are meant to be coupled with a sub system, or amped up pretty good, to get the response out of them. If you go polk and go with the MOMO edition speakers, you will need an amp.
I have a polk 10" sub, and a pair of momo 6.5"s that definately need an amp that I could sell you for a not so bad price let me know. By the way Zapco amps are the shit!
Hookers need love too!
What we do in life echoes an eternity
<img src='http://vfs.com/~3d43patrick/rookiesig2.jpg' border='0' alt='user posted image' />