100W x 4 @ 4 Ohms, which your amp is rated for, is good for any good quality 6.5" component speakers. Set your HPF to around 80-100 Hz depending on how loud you like to listen to your music. If you get a CDT set that has a more bass heavy woofer you might be able to set the HPF lower and still listen at high levels, depending on how well you install them.