Most Nissan 370z owners looking to get the most from their VQ37VHR engines consider aftermarket test pipes as one of their first mods. But how powerful of a gain do 370z test pipes provide, and at what cost? In this piece, we tackle the additional real-world performance gains, installation considerations, and legal dilemmas regarding the use of test pipes on 370z.
What are Test Pipes and How are They Used?
Test pipes are straight exhaust pieces that substitute the catalytic converters. Unlike catalytic converters that use a honeycomb structure to filter out harmful emissions, 370z test pipes are hollow pipes made to optimized exhaust flow. These pipes remove restrictions and decrease backpressure, letting the engine get rid of exhaust gases more effortlessly.
So, what’s the outcome? Enhanced horsepower, torque and throttle response – especially in the mid-to-high RPM range. Nonetheless, this form of alteration does incite debates. While test pipes unlock hidden gem power, there are laws and environmental concerns that every 370z owner needs to acknowledged before switching.
Investigation of Real-World Horsepower gains from 370z test pipes
One of the biggest concerns for the 370z enthusiasts out there is: how much gain do I get? The answer depends on multiple factors including whether your vehicle is naturally aspirated or turbocharged, tuned or untuned, and paired with several other exhaust modifications.
Test pipes should give you an increase of 5-15 horsepower at the wheels on a stock 370z. The largest gains can be found in the upper RPM range. While, when matched with a proper ECU tune, the gains should be between 15-25+ horsepower due to the engine being able to utilize the improved exhaust flow more freely.
Dyno tests from credible tuners have shown that 370z test pipes do help the VQ37VHR breathe above 5,000 RPMs much better. This is also where the factory catalytic converters are the most restricting, and removing them allows the engine to rev much more freely.
That said though, the horsepower increase for the test pipes isn’t as much as some might expect. If your ideal is for larger increases in power output, forced induction (turbocharging, supercharging) will deliver much bigger results. But if you want fairly lower cost bolt-on modifications, 370z test pipes are a good way to improve/revive the engine’s higher RPM performance.
Sound Changes: Throatier, More Rasp, or Just Louder?
For those installing test pipes, one important factor to remember is the change in exhaust sound. The 370z has a distinct V6 roar, and removing the catalytic converters will definitely increase the volume and change the tone into something more primal.
With 370z test pipes, you can expect:
Increased exhaust volume (especially at full throttle)
A somewhat sharper, more aggressive tone
Some raspiness at certain RPMs, based on the exhaust setup
Some owners love the unfiltered sound, while others think that it is too aggressive. If you are worried about excessive drone or rasp, using a high-quality resonated cat-back exhaust with test pipes can help tame the sound.
Legal And Environmental Considerations
Understanding the legalities of removing catalytic converters is important to the conversation, so make sure you understand the legal side of things before installing 370z test pipes. It’s illegal to remove catalytic converters in the US due to federal emissions law, and a lot of states, like California, have draconian smog checks that will absolutely fail a car using test pipes.
Even in states without emissions testing, running test pipes technically violates the Clean Air Act, which can lead to fines. Some owners try to circumvent this by swapping back to stock cats for inspections, but this can be a hassle.
Removing a catalytic converter can legally be done, but it does have some environmental consequences. Being that it is a car part that has been designed for pollution control, removing it will contribute to more pollution being produced. If you are concerned with the environment, high-flow catalytic converters from manufacturers like Berk Technology or Fast Intentions offer a compromise whereby thrust exceeds stock while still abiding by emissions regulations.
Installation and Tuning Requirements
For someone that has basic mechanical knowledge, installing 370z test pipes is an easy task. The following steps outline the procedure:
Using jack stands, securely lift the vehicle, or use a lift.
Remove the factory catalytic converters (be prepared to use some force as stubborn heat cycles may create issues).
Use new gaskets to prevent leak and attach the test pipes.
After removing the secondary oxygen sensors monitoring catalytic counters, adding test pipes can result in a check engine light (CEL) coming on. In order to avoid this, you will require:
O2 sensor spacers (temporary alternative that does not always work), or
A proper ECU tune (most effective fix as it also increases vehicle performance).
In addition to preventing CELs, retuning the vehicle ensures proper engine functioning by maintaining optimal performance under increased exhaust flow. Without retuning, the full horsepower potential of the 370z test pipes may not be realized.
Are 370z Test Pipes Worth It?
The response varies according to your objectives:
✅ Worth it If:
You are pushing for the last NA horsepower.
Emissions testing is not an inconvenience.
You appreciate a louder, more aggressive exhaust note.
You plan on a tune to maximize gains.
❌ Not Worth It If:
You are required to pass strict emissions tests.
You prefer the car more silent, or less refined exhaust sound.
You aren’t willing to deal with potential CEL problems.
Test pipes are a popular and effective modification for track-focused builds or weekend toys. However, for daily-driven 370z’s, especially in regulated areas, high-flow catalytic converters might be a better option.
Final Verdict
While 370z test pipes do offer significant gains in horsepower, especially with a tune, they also offer trade-offs in sound, legality, and emissions compliance. If these compromises are something you are okay with, then they are a performance upgrade. If not, high-flow catalytic converters provide a middle ground.
At the end of the day, test pipes aim to unleash the 370z’s full potential, but be sure you have all the information before making the switch.