I bought a turbo timer a couple of weeks ago for my Z, got fed up with sitting and waiting. Was also worried about the implications with the alarm, mine cuts in after 15 seconds, I usually wait until the engine has stopped before setting the alarm. My timer, like most, has a cut out wire to the handbrake so if anyone does try to steal it as soon as they releas the handbrake the engine cuts out. usually you have to hammer the turbos to get a high setting on the timer but if you let them cool down with a steady drive timer setting is only about 15/20 secs anyway.