Viper 791xv, 2003 Mazda 6

Can you post a digital pic of the sensor.  I'm thinking that you might have been screwed on the sensor.  Did you buy it on flea-bay?  (just kidding, I buy lots of stuff from that slum -   :).

Seriously though, to me, it doesn't sound like a TWO stage sensor.  You have the right idea mounting it to something solid.  I'd recommend getting rid of the lock ties though.  Screw it in TIGHT as possible (without stripping) to the inside firewall of the car, down by the gas pedal (but out of the way).  This should pick up most shock.  If it's a single stage sensor, then set it as sensitive as possible and then test it over and over, and slowly adjust it back to where you want it.  I always don't mind having a few days or nights of falsing and adjust mine a little each day until I achieve the desired result.  I'd rather have mine a little too sensitive and catch a criminal in the act, than have it not be sensative enough.  We had someone do $1,200 damage to the passenger side handle of our car without the alarm going off.  This is why I went out and bought a Clifford AvantGuard 5.  Extremely sensitive Omnisensor with that.  It will pick up me lightly flicking the back bumper and the sensor is screwed into the firewall above the gas pedel with FOUR self tapping screws.  It picks up everything.  It started lightly raining out last night and my warn away buzzer kept growling.  Guess I'll have to adjust the sensitivity down a bit.  But it's great having such a sensitive shock sensor that I can make as sensitive as I want.

Good LUCK!