Texas is No Partner to the Dual Exhaust on Your Truck

The State of Texas has a proud history of racing; such greats as Shelby and Bondurant have graced this state’s register of residents. However, our racing prowess will not stop the Texas Commission on Environmental Quality’s (TCEQ) from interpreting their automotive emission rules quite strictly. So strictly in fact, that your custom, mandrel bent, stainless steel, 3″ diameter, chrome tipped, all out, dual cat, dual exhaust system (or any aftermarket system…really) may very well be violating the rules and regulations of Texas.

So, when can you have a dual exhaust system you ask? Well, you can have a dual exhaust on your car when “the vehicle’s manufacturer certified an identical engine-chassis configuration for that model year of vehicle or newer that includes such an exhaust configuration.” Wait, what?

Here’s an example. Let’s say you purchased a 2003 truck with a V6, and for that year the manufacturer only made that truck with a single exhaust. If, over the coming model years for that generation truck, the manufacturer never put a dual exhaust on that vehicle, you can’t either. However, if the manufacturer put a dual exhaust on the 2004 truck with a V6, then you are free to bifurcate the exhaust on your 2003 truck. However, no matter what exhaust you put on your vehicle, all the components – including the catalytic converter, must meet with EPA and TCEQs requirements. So why all the bother?

Well, the TCEQ blames backpressure. Backpressure is the amount of pressure the exhaust gas exerts within the exhaust pipe. In other words, you have higher backpressure when you have a restrictive exhaust. A restrictive exhaust allows exhaust gas to flow less quickly. This means that the exhaust gas spends longer in contact with the catalytic converter components; thereby being more, well, converted. A dual exhaust with dual catalytic converters could have really low backpressure, thereby allowing the exhaust gas to zoom past and not maintain enough contact with the catalytic converter.

That’s all fine in theory, but given all of our modern technology, are we at all concerned? Well, the TCEQ is officially still concerned, but we have yet to hear of any case in which an inspection sticker was denied because a certain vehicle did not originally have dual exhaust. If you know of one, let us know! To learn more about ‘tampering’ with vehicle exhaust, read what the TCEQ has to say about it.