I was one of those who missed out on buying the TPMS on my 997. Man that was dumb on my part. I went with an LED Tire Alert Pressure Indicator from vechnicallight.com http://store.vehiclelight.com/airalert.html . I went out in the garage last night and notice my left rear tire indicator was flashing red. Turns out my tire was low. Went to the station and added air and everything is now good.

Hey it works.