Hey all.. just picked up an 05 g35x with 70k for $13k. Awesome car! This is coming from a guy with a 620hp Evo

My questions are..

1. It appears most of the audio has been upgraded.. Pics below. I would like to switch to a double din which I assume would be trivial given the work that has already been done?

2. There is a rockford amp installed.. is it safe to assume the stock bose has been removed or bypassed?

3. I have a random off\on switch under the dash and an antenna on the windshield.. I assume these are not OEM?

4. Finally, there's a bunch of water in the spare trunk area.. but the carpet is dry.. I sealed up the rubber grommets.. anything else I should check for?

Thanks!