One of the main worries of spending a lot on your sound system is theft.
The best way to combat this is to hide your ICE, and to make it difficult.
If you don’t have central locking and dead-locks, get an alarm. If not just install a simple flashing LED. Not many criminals will take the chance to find out whether or not the alarm is real.
One of the silliest things I see is people putting windscreen stickers in their cars? Why would you advertise that you have a thousand pounds worth of amplifiers and speakers?
Also it’s important not to leave your speakers on display. A lot of people leave their 6x9’s exposed in their parcel shelf. It’s actually very easy to cover these with some acoustic carpet.
To do this you just need to get some spray glue, and away you go. It's pretty easy once you’ve done it once. Spray on the glue where you want to start. Put the carpet down and smooth it flat until you need to re-glue. Keep repeating these steps until you come to the end and then trim the edges and glue them to the underside of the parcel shelf.
A final note, take your head unit facia plate with you when you lock your car up for the night! Even if it does get stolen you have the satisfaction of knowing it's useless to them!