Hertz all the way. I have the HSK's, and they sound unbelievable.

 

Herts HSK 165 FTW!!! Those things rock! I have used them in the S a WRX and a Civic, they win my money.

 

when I got my car a month ago it came with a Polk system ala the Lucid variety. The system plain sucked, I've got a set of Alpine components going in this week, taking my time and installing them myself. They sounded good at the shop I bought them at, we'll see how they work in the car with my Sony xplod deck. No amp or sub. I'm not an adiophile, I just wanted something that is better than what was in the car, it should work fine.

 

I liked the 165KF set I auditioned, but thought the K2P was a bit bright/forward sounding.

I have a/d/s components, which are the original design for the PPI set recommended here (Directed Electronics bought a/d/s, PPI, Orion, and others a number of years ago, and while the current stuff is made in China instead of in Arizona, they still sound pretty good).

They do produce a nice midbass, but I am using them with a sub. A component set with fantastic bass response is the Pioneer PRS 720 kit, but the included tweeters have been called bright by some. Could always replace them with something else, or try to source the mids standalone.