As many installs as i have done it saddens me to even say that one of them was jacked and everything stolen. That is why I am going to try to give some people some tips to prevent this.
Do not show off
This may seem pretty obvious but the fact is many people do it. It is one thing to drive down the road with the system up and the windows down. But it is another when you are a mile away from your house or pulling into a parking lot. Feel free to do it when you leave if you are not heading right across the street to another store.
Another part of this is if you are at a "car show" that is not organized such as a night parking lot gathering. Be very careful who you show your setup to. Especially in my area this tends to happen a lot where someone will show there system off and end up 2 days later getting it jacked.
Tint rear window
Well most likely when you had a new system put in you installed a rear view camera. So you probably do not turn around anymore. If you have anything more than a head unit such as a sub or amp installed in the trunk and it is not hidden. Your best defense from thefts eyes is to tint your rear window.
Shops
This is how we believe a install I did got jacked. A fellow friend and install went to a shop to believe it or not get tint put on. Within 2 days later the car and system were gone and were found 3 weeks later a half a mile form the shop. Anyway watch who you let work on your car. I am not trying to scare anyone and you all probably make good judgment calls on who you choose to work on your car. None the less tread softly.
Alarm
As of right now I do not know many z's that have had an alarm installed. However there is always time to start. Even a "fake alarm armed light" sometimes can be enough and are very cheap and easy to install.
Fake faceplate or removable
I know most z owners own double din head units which can not be removed. No worries though. If you go on ebay or google and do a little searching you will find fake stock faceplates. These go right over your real one without harming anything and will make it look as if a stock head unit is installed. Or if you have a single din most likely it has a removable faceplate. Remove it. It takes a few seconds and you can even put it in your glove box if you really dont want to carry it around.
Distance in parking lots
This probably most of you do anyway. But if your car is in the middle of no where in a parking lot and under or near good light. You have a very good chance that no one will touch it.
Blanket
This can help a lot in the case of a trunk with an exposed amp or sub. Using a fleece blanket that is close to the color of the carpet. You can easily cover up most of what is back there. This will give the illusion that there is nothing back there. Works well at night.
Kids
Even I know kids like to go on and on about who has this and who has that. That can be overheard by someone you did not want to hear it. Or "if you do" let them use the car
talk to them about what you want them to not do with the stereo while using the car.
I hope this helps some of you keep your systems safe and longer. If you have any questions please ask.