Test pipes resemble catalytic converters except for their honeycomb interiors. This makes them a suitable replacement for cats. However, it is important to remember that a test pipe will give the car a noticeable audio boost and a bit more power.
Despite the possibility of replacing a catalytic converter with the test pipe, it is not the best long-term solution. Test pipes are an excellent short-term fix, but I would suggest buying another cat when you have the opportunity.
Keep in mind that most states do not permit the use of a test pipe. Moreover, your vehicle will fail smog or emissions checks if the pipe is installed.
I provided a great deal of insight into test pipes, but do you even know what they are? Let me explain.

What is a Test Pipe Catalytic Converter?
A test pipe is located at the same place as a catalytic converter. It reduces the backpressure by a significant amount. Due to this, the car is able to get an unrestricted engine flow, allowing the driver to access the car’s full potential.
Most catalytic converters will not decrease the backpressure but rather increase it. As a result, it prevents you from utilizing the actual horsepower of a vehicle.
The biggest drawback of test pipes is their inability to convert harmful gasses into harmless ones. Hence, these are not eco-friendly products. It is the sole reason many states prohibit their use.
Also Read: What is Pre Catalytic Converter?
Is a Test Pipe a Catalytic Converter?
While test pipes and catalytic converters share similarities, their core is quite different. Let’s look at the top three key differences between them to clear things up.
1. Conversion
Catalytic converters are environmentally-friendly components that transform hazardous gasses into harmless compounds. On the other hand, a test pipe is incapable of converting emissions.
2. Backpressure
The test pipe lowers backpressure, allowing a vehicle to reach its maximum power. Unfortunately, cats are what cause the backpressure to rise.
3. Sound
With test pipes, vehicles sound louder. The sound becomes even deeper and more appealing with the addition of a resonator. As opposed to that, cats retain the stock sound.
Does Straight Pipe Mean No Catalytic Converter?
Straight piping your vehicle means there will be no catalytic converter in the exhaust system. Technically, it is impossible to install straight pipes without removing the catalytic converter.
Moreover, straight piping is meant to deliver a cleaner exhaust, which can’t be achieved with a catalytic converter.
The cat is not the only component you remove when straight-piping your car. The resonator, muffler, and catalytic converter will also need to be discarded.
Remember that removing cats is against the law in the United States. It will be tough to pass emissions if your car does not have it.
In case you still want to straight-pipe your vehicle, please refer to my detailed guide for passing the emission test.
Do Test Pipes Remove Cats?
Removing the catalytic converter before installing a test pipe is necessary since they are both mounted at the same spot. Hence, the cat will not exist in the system once you install the test pipe.
As catalytic converters are required for smog clearance, many motorheads choose not to use a test pipe to avoid breaching the law.
Can I Replace a Catalytic Converter with a Straight Pipe?
You can use a straight pipe to replace a catalytic converter, just like test pipes. It is because there are no distinctions between straight and regular test pipes.
Unless you are dealing with resonated test pipes, replacing a cat with a straight pipe is the same as replacing it with a test pipe.
Read Also: Does A Cat Back Exhaust Replace The Catalytic Converter?
Conclusion
As I mentioned in the article, the test pipe can be a good replacement for catalytic converters in the short run. However, if you are not concerned about the noise and the fact that it is not eco-friendly, test pipes might be an effective long-term solution.
You may also read my article about whether straight pipes increase MPG if you are interested.