it all depends on who you advertise it to when you go to park it and show it off too. i had over 4k in my car for years never got messed with and i lived in a pretty bad neighborhood for a while with it but i didnt advertise it around there either even though someone would probally have guessed ther was something in it form being dropped an inch off the ground with 18"s tucked up in the fenders and neon all under it with pop trunk with no alarm. i have all of the stuff in my truck with no alarm on it .
bottom line is if someone wants it bad enough an alarm isnt going to stop them from getting it. ive watched people break into cars and steal everything out of em with the alarm sitting there going off in the middle of broad daylight in a crowded parking lot like at the mall and people just walk right by them and never say a word. pretty much dont even pay them no mind and just go about there business.