Sensitivty gets worse per distance of unit?

Hi guys, legacy Code Alarm (voxx) CA100 system on a 2004 silverado base model, LWB pickup. Got a question here about my alarm's sensitivty. It has two modes, like many others, Warning and Alarm. I have both modes set to "14/15" which is 1 setting under maximum sensitivty. Up front it does "OK" on the front bumper if i slap it hard enough it will go into warning. If i bang on the driver side window or door pillar, it takes a rather hard bang to reach an alarm (the alarm module is on the drivers side of the pickup right under the steering column). This is concerning to me because I felt at max sensitivity it would be a little more (much more) sensitive than that. On the rear bumper, I can kick, hit, jump on it, everything shy from an alarmingly hard kick will cause it to warn/alarm. Even with the rather tough sensitivity meter on this unit, it still takes too much to set it off, a car could practically rear end me and i doubt it would go off. Do I need to relocate the module? Are sensitivty sensors usually separate from the module? Mine looks like everything is close to the module itself. Should it be operating a bit more sensitive than this? The truck is a long wheel base vehicle so the distance from the module to the rear bumper is somewhere around 13-15 feet give or take.-8track