Don't get a KARR brand alarm. It goes into your factory stuff. It has a starter killer and all that. Is just like the PATS, but now I have two systems running.......
The dealer put in a KARR alarm on mine as part of their "standard package" for all cars. I wanted it off, but the bank said no, it had to stay. They like these extra items. Have someone good wire your alarm. The monkeys at the dealership jacked up when they installed the alarm my car came with. There are Scotchlocks everywhere, plus the wires weren't cut to length, etc.,etc. It looks like my redneck cousin Bubba or a 5 year old did the install. It is so sensitive, even on the lowest setting. I hate it. I had to discount the horn by pulling the fuse so it would shut up. If someone shut their door two cars over it would go off. I tried to remove it by just disconnecting the wires, box, etc. The car wouldn't run. I re-installed it, and it ran fine. I think it is linked into the existing system. Don't get an alarm that does this. I hate alarms. If somebody wants your car it is gone. If they want your equipment, it is gone. It only takes a few seconds to steal things outta a Mustang.