For Those Of You With A System But No Alarm

My amp and 10" sub are on their way, and I started thinking about protecting them from theft (I realize you can never be 100% safe). I called the shop that put in my remote starter, and they said to add an alarm they would have to take the starter out, and put a combo in...$249. That's definitly out.

I am thinking about using some frost king 1. to prevent rattles 2. to improve SQ and 3. to limit the noise outside the car.

Other than not bumping at school or the mall and then leaving my car unattended, and shutting the sub off anywhere near my house, I'm not sure if there is anything else I should do to help keep it in my hands and not some crook's.

I live in a decent neighborhood, so I doubt it would get stolen here, but with work or school, I'd rather be safe than sorry.

Any tips?