Recently purchased a used 2007 F150 has the factory installed alarm...the dealer had installed a KARR alarm which is extra...I purchased the KARR but now have doubts as to which alarm is the best and do I really need two alarms...

 

If it had the factory alarm (not just RKE) I'd have gone with that...

In our Honda the Karr alarm gave us trouble when we tried locking it from the inside. It would automatically arm the alarm, and disable the ignition.

Good if your car was being stolen, bad if someone was following you in a dark parking lot. I had them upgrade my alarm (only a few months old) and now it arms if you lock the door manually, but not if you use the switch. Better than before when it'd arm regardless of how you locked it though.

 

I've had the dealer installed Karr for 4 1/2 years. I like it fine. Never had the factory, so can't compare.