Here a couple I got recently to put into a car and they are unbelievable.
Illiusion 6 inch at solen.ca
Scan speak revelator tweeters at madisound.com
6.5 subs at ddaudio.com
Due to space limitations, I am using the 6.5 digital designs as subwoofers and they are amazing. They play as low, smooth and hit as hard as any 8 inch subwoofers I have ever heard. They are also only $ 129.00 a piece.
The Illusion carbon series are incredible for tight space limitations, specially at the price.
I also use 130 tweeters from Morel that you can find at madisound.com. They can build you a crossover to meet specifications of the speakers you choose. You build a custom speakers array that will out perform any component system under $ 750.00 to $ 1,000.00 through these sources and save a whole lot of money.