oh, and here ya go, from your own states emissions site:
"(a) Any person owning or operating any motor vehicle or motor vehicle engine on which is installed or incorporated a system or device used to control emissions from the motor vehicle in compliance with federal motor vehicle rules shall maintain the system or device in good operable condition and shall use it at all times that the motor vehicle or motor vehicle engine is operated.
e) No person may sell, offer for sale, or use any system or device which circumvents or alters any system, device, engine, or any part thereof, installed by a vehicle manufacturer to comply with the Federal Motor Vehicle Control Program during actual in-use operation of a motor vehicle on Texas roadways. A notice of the prohibitions and requirements of this subsection shall be displayed at all motor vehicle parts, supply, repair, alternative fuel conversion, or other vehicle service facilities in Texas which sell, offer for sale, install, or offer to install any vehicle emission control, exhaust system or device, aftermarket alternative fuel conversion, or engine. The notice shall be displayed in a prominent and conspicuous location near each consumer entrance way and service counter. The notice shall read: "State law prohibits any person from selling, offering for sale, or using any system or device for the purpose of circumventing the emission control device on a vehicle or vehicle engine. State law also prohibits any person from removing or disconnecting any part of the emission control system of a motor vehicle, except to install replacement parts which are equally effective in reducing emissions. Violators are subject to penalties under the TCAA of up to $25,000 per violation." This notice shall be no smaller than 8 by 10 inches (20.32 cm by 25.4 cm) and shall be clearly visible to all customers"