It's not that you want to use crap-*** speakers with an aftermarket HU, it's just that with an external amp, it helps clean up the noise a little bit. You really can use whatever brand/cost speakers you want even though you're not using an external amp.
As for 3way vs 4way, I perfer 2 way even if we're not talking about separates/components. A 3 or 4 way just adds too much emphasis in the upper midrange (the 5.5-8KHz) and then is much too sparkely up top (15+KHz). I perfer a 2-way with a silk, textile or other soft domed tweeter. However, car audio tweeters are typically always hard domed ***I'm using Crutchfield because it's easy to search through them***These Infinity's wouldn't be too badhttp://
www.crutchfield.com/S-D...012SI
These Alpines would also be pretty good.
http://www.crutchfield.com/S-D...S17C2
This is the MClass 6.5" by Memphis Audio. I have these in the doors of my explorer. The cost is pretty good, they have an external x-over and I believe they're bi-ampable IIRC. Also the tweeter pivots, but only around 30degrees or so. There are better speakers out there, but they're not bad for the money.http://www.memphiscaraudio.com...id=16Carbon Fiber
Elemental Design has a line of separates that might work for you?
http://edesignaudio.com/produc...r=USDBTW, stay away from Kenwood, Sony and Pioneer if you can help it. They're not bad, but you can do better.
Modified by Looneybomber at 5:16 AM 8/11/2006