Improving the 'range' of your existing alarm system

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Hi bros.

Just wondering if any of you here have any tips on how we can extend the 'range' of our car alarm system? Say for example, stock allows us to be able to activate our alarm system when we are 10m away ... Let's say if we do some mod to the system, we're able to activate our alarm when we are 20m away ... Any one got any tips? Btw, I'm from Singapore and driving the Vios which is the equilavent of the 'Yaris Sedan'

Basically I just installed this device which allows me some pretty neat functions like remote start/stop, pitstop, turbo-timer (nope, I ain't got one yet) ... The thing is I find that the stock alarm system I am on has a pretty short 'alarm range' and I am looking for ways to extend or optimise the range. I was wondering if any of you bros here have actually been successful in doing it? I was told that someone did manage to do it by putting in an extra antenna on his a-pillar ... Just wondering if anyone here did it and if yes, if you could point me in the right direction. Many thanks!