it all depends on how you set up your car....

I got an alarm with my tint for $250 installed. I also removed my door locks.

its not the greatest alarm (autopage), but it has a motion sensor, and its set at a good level (not too sensitive).

basically, the biggest thing to worry about is if the theif has access to the hood to disconnect the battery. There's a few ways to deal with this, the main being to rig up a back-up battery. My car was broken into once, because the person managed to pop my hood release cable, disconnect my power, and break a window and unlock a door manually.

without door locks, there's no way to enter the car if the power is disconnected. The only way to unlock the doors is either a key or the power turned on, but if thats the case, then the alarm will be blaring... I hope this makes sense h: