Just had my truck smogged for registration renewal ...
Tailpipe sniff test at 800 and 2300 PRM (CO2, O2, HC, CO)
Funtional tests: EGR and Gas Cap
Visual Inspection: PCV, EGR, O2 Sensor, Fuel Evap Controls, Spark Controls, Wiring to Sensors, Fuel Cap, Cat Converter, Fuel Injection, Vac Lines sensors and switches, Malfunction Indicator Light.
I forgot to ask the guy if he connected to OBDII, but I'm sure he did.
He told me that at the state run classes on performing smog checks, they are taught to look especially close at trucks equipped with additional gauges ... most likely the vehicle is modified.