Put no stickers on the car whatsoever. Don't give a "good" thief the information he needs to come back next week with the tools to take care of "XYZ" alarm system.

Keep them guessing. Part of being security conscious(sp?) is never letting them know you know. I have a security system in my home. No stickers.. no nothing. The only thing that hints security is the sign that says "German Shephard on Guard"..... That's one I don't have to explain.