Sounds like a short within either the wiring or the alarm brain....:thinking:

Does the alarm "think" one of the doors isn't fully closed when you arm the system? Does it chirp at you- when you know the doors and trunk are shut fully?

If so, a shim on the door / trunk at the position of the appropriate switch might work as an interim fix.

Oh, is your GS-R a sedan or hatch? Only wondering because on my 97 LS 2dr, one of the door switches has already failed-and it may be a part of your problem. More doors, more chances for a switch failing.

Anywho... hope my input helps some..

Dave.