I used to love DEI alarms (Viper,Python,etc) but now I recommend Compustar their 2-way is amazing and its has long range almost 2-3X that of DEI.
BUT...none of thse will stop ur car from getting scratched...i had the same problem got scratched...repainted got scratched again left it like this till i catch one of these ****ers so they can pay for it.
But if you want a alarm for security get 2-way Compustar.....DEI used to be amazing until they expanded their business beyond just alarms.
Other then that i would recommend waiting to catch the ****er......or maybe you can figure out a way to shock this ****ers when they touch the car....lolololol
