you should also test the neutral safety switch once in a while. it's possible that the transmission's neutral position switch may go bad and not send a proper ground signal out when the vehicle is in gear and allow your vehicle to remote start in gear!
it's easy, sit in your vehicle while it's off and have your foot over the brake pedal. shift the vehicle in gear and try to remote start. if the neutral safety switch is working then the vehicle should not remote start.
also, i typically wire up the vehicle's parking brake wire to the neutral safety input of the viper alarm as well. obviously, you shouldn't rely on this wire to safely remote start a manual transmission vehicle.
netZ