If you know what you are doing 2 minutes tops to drive away, regardless of alarm type, it will be silenced within 20 seconds.
You don't even touch ANY of the alarm/immobiliser wiring, but not posting on here how it is done.
This is to DRIVE the car away, I used to repo, my best advice seriously is get yourself a seperate siren(maplins etc) hide it as awkwardly as you can behind dash etc that goes off linked to a latch on a relay as this is awsomely disorientating, you just can't think straight with 100 odd db going off in a confined space.
All this garbage about thieves will just lift it etc is just that garbage, they are not going to take a serious risk for a relatively low value car, as trucks with hydraulic cranes etc are noisy and easy to see, pro's don't work this way either, they park in front with atruck drop the ramp attach a cable and drag the car in, though of course lot sof other ways.
Make it as unappealing to steal as you can, if a pro wants it he will get it, but with low value cars he won't want it, or the risk for the return(£££).
So you beat the opportunist, they are lazy which is in our favour, make it harder than the next guys and they move on to someone else's car.
Always park in a prominent position, when I go to tesco etc I always park car all on it's own, so it stands out a mile if anyone goes near it, if the alarm did go off it's plain to see from which car it is coming, thieves don't like attention, simple measures like this work.
The trouble with alarms if if fitted with lots of extras like beeps when someone goes near you will soon stop looking everytime you hear a beep, more impoirtantly so will your neighbours, especially any that is used to false alarming, "oh bloody hell thier alarms going off again, I'm getting pissed off with this" is a common comment.
Mechanical deterents have thier place as well.
tabetha