I came to the stark revelation that my 06 SE Roadster does not have tire pressure sensors when I picked up a screw in one of the tires and just happened to notice it when i was filling up w/petrol. My question is does anyone know if I purchase factory sensors and install is the vehicle equiped to monitor on this model w/o any upgrade? I do have a TPMS light that comes on when I start the vehicle but it obviously does nothing! Are there any other options available to me? P-J