read above my alarm is still on the car the only thing i removed is the Engine loom which is both ECU's and all sensors etc its easy too see as you remove what needs to go. Car loom (lights horn etc) all stays the same so wont afect your alarm...

my pins didn't need changing as it was a FRST loom to start with. If you use a standard EFI loom there are a few pins to change yes.