i am going to add a shock sensor to my existing car alarm.

I also want to add a siren in my car.. a LOUD ONE. Like really really really loud. Does anyone know what i could do. I don't think the factory alarm is loud enough. I need an alarm you can hear from all the way from China. Any suggestions for a good alarm?

I'm really afraid someon's gona steal my stuff Anyone know of any good insurance that products from car theft (like protects for rims, foglights, etc)?