The good guys that can code hop, and are willing to make the gamble on the brain of the unit being under the dash, and that there is not a backup power supply for the alarm can disarm an alarm in 3-5 seconds with 2 people....
Really quite simple.
First off, there are 2 kinds of Code Grabbing. (1) Thief activates grabber in active time near your car as you arm/disarm. (2) Thief scans for your code when you are away & the vehicle is armed. Many good quality car security alarm systems (DEI) have a 'rolling code' feature which changes remote transmitter codes every time you arm/diasarm. Also, there are now billions of different code combos. Even if a good thief tries to scan with a fast scanner, it can take a while to finally lock on. Even with that, if I am correct, the alarm control module can shut down any attempts to hack codes after so many attempts. The use of 'passive arming' (armed after last door is closed) also helps with code grabbing so no RF signal is sent & no code can be grabbed.
Just to state: Code Grabbing is not as wide spread in the US as some think. It has been more of a problem in Europe. I have a old 1996 issue of DEI's 'Security Sense' mag where there is a in depth article on code grabbing.
As for your other comments other than code grabbing, even IF the control module is under the dash with no back-up batt, you can still make it hard to disable by installing high pitch piezo sirens near the unit to make it painful to the ears to attempt to disable. Also, even though I do not recommend to many physical harming security measures for car security, you can wrap razor/barbed wire around the alarm control module IF it is not hidden well. Also, get a hood lock system or relocate your hood release lever to prevent easy access to disabling siren, etc... under hood. Remember to wrap up your color coded alarm wires with either electrical tape or wire loom to blend in with your stock wiring to confuse them.
TO SUM UP: Not to say there is no way around anything, but with enough knowledge & planning you can learn & make it as difficult as possible! Just think like a thief! //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif