i use to work in walnut creek on n.main.:thumbup:

you can keep the stock HU, but i always recommend that you do swap it out for another, since you will need a better signal to your amps.

you are planning on putting an amp to the kappas? if so i definity recommend changing the HU.

i also love Pioneers organic displays.:thumbup: what exactly is the price range those the model you mentioned?