It's a pain in the butt to install the navigation unit on a non-navi Accord, according to many people. It's not a simple swap of the headunit. Lots of stuff to do. You gotta run wires...etc. Would have been better if you just bought the car with navi.

I believe the flat antenna is for XM on the normal Accords. But here in Canada, we don't get the XM option. As for our antenna that sticks up, that's our antenna for radio. Normal Accords have them in their rear window. But for us, it sticks up there because of interference from the battery.