I bought some pricey drivers, although I can't recall the brand off hand. Infinity or Kenwood I think. Not really worth the money. They do one thing really well: super bright, steely treble. That combined with the onboard 3-band EQ on the Nak and I've got treble to spare. But I felt I got better sound out of the factory paper cone cheapies. Probably more efficient, a better match to the amp, something like that, I dunno. Unfortunately when I got around to installing the CD-400 the original drivers were all dry rotted. Now that's what I call break-in, when the cone flakes into dust in your hands!
Maybe that like what they say about guitars; they sound their best when the wood is so thin that it's on the verge of breaking. Maybe the same holds true for speaker cones. The fancy schmancy aftermarket speakers are built nice and probably won't rot, probably have better specs than factory, but they just don't sound as good. There's lumpy bass, steely treble but not much going on in the middle. Perhaps that papery, honky sound of full-range drivers is condusive to car audio acoustics.
I would experiment with cheap full range drivers if I were to do it over. No sense in spending hundreds in my opinion.
