I've been reading the various posts ... very helpful and I want to thank everyone for their input and insightful comments.

I just bought a 2005 S (w/o RF system) and am in the process of connecting the harness to my CDA-7875. One quick question for anybody knowledgeable - off of my head unit is a black ground wire ... off the two-piece harness are 2 separate black grounds - one labeled "amplifier ground" and one labeled "chassis ground." May be a stupid question, but I want to make sure I do this right to prevent any unneccessary noise - Do I connect the head unit ground to one of these two grounds on the harness, or do I run the head unit ground directly to the chassis? What did you guys do? Any input will be greatly appreciated ... thanks.

While the harnesses (factory and the wiring kit) had all those extra ground wires labeled for various things, my new head unit only had one ground - so none of that other stuff really mattered.

I grounded mine to the chassis - there's a bolt on each side in back of the opening where the HU slides in. I used my tester to "prove" the one on the right was a good ground and used that. Sandwiched the ground connecter around the bolt between the two brackets that the bolt holds together.
No noise at all, not even on AM.

Thanx X -

Think it's okay to just cut them off then?

I wouldn't cut them off - that's kinda final. Never know what ya might be installing in a few years.... might end up needing 'em someday!
I just wrapped the ends in electrical tape.