Actually, because I am a bit of a tinker'er - sometimes to my detriment
, after posting above I decided to swap the oem dash 8ohm speakers back in for a test real quick. To me, even though a lesser quality speaker, the overall balance with the 8 ohm dash stockers is better than with the 4 ohm KS 3.5's.- you can actually hear the front door 6x9's, instead of them being mostly washed out, and you don't have to fade to the rear like you do with 4 ohm dash speakers. I'm going to run it like this for a few days and see how I like it, I don't run a lot of volume but do like it to sound good. Unfortunately, there is not a lot of selection of quality 8 ohm 3.5's that I have found.
As I posted in another thread I replaced both front and rear door speakers with Pioneer A series 6966R's - not the shallow mount G series. Overall it's an upgrade of course, but since keeping the 8.4 HU there's only so much that can be done.