When I develop a component with our engineers, especially for a platform like the Toyota GR Yaris, my objective is simple: measurable improvement without compromising OEM logic.
Our enclosed engine airbox had to achieve this objective while using the OEM filter for ease of service. It also needed to work seamlessly with both the OEM ECU and with Aftermarket ECU’s, such as Syvecs and Motec units. All of this while remaining both affordable and built professionally, in high volumes.
This article documents the final validation of our PIII GR Yaris Airbox Intake, using real dyno data, stock-mapped vehicles, and direct MAF verification. Everything written here is based on controlled testing and confirmed results.
What to expect from upgrading your OEM or Aftermarket Intake to our PIRAS Motorsport unit?
- Increased power
- Increased transient response
- Increased induction noise, with lift-off swooshes
- Decreased engine IAT Temperatures (Intake Air Temperatures)
- An OEM+ look under your hood
As you surely know, the engine in question is the Toyota G16E-GTS, and the focus throughout development was airflow efficiency while maintaining factory ECU behavior.
We had to use all the tricks up our technical sleeves…
A transparent disclosure for our new friends:
The GR Yaris Airbox has been the first high-complexity product we brought to the market at PIRAS Motorsport. Three different production companies involved and a new warehouse.
Since Internet mostly remembers issues instead of positives, you may read that we experienced some initial quality issues, affecting units built and sold in Q3-2025.
All issues have now been solved, and product lifecycle management is in place, bringing small iterative improvements thru time. Current production has zero quality issues.
We currently hold a stock of GR Yaris Airbox units in our warehouse.
Although we were a startup, we managed all issues with quick email replies and phone calls, and each affected customer got a replacement for the defective parts or the entire Airbox. I strongly believe in Customer Service as a defining pillar of our company.
Today you can buy our products carefree, knowing there are no quality issues, and be sure to live the best possible experience in technical support and customer service if needed.
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Development Objective: Performance Without Calibration Risk
From the beginning, the intake had to meet a non-negotiable condition: factory MAF scaling had to remain 1:1 with OEM readings.
If an intake alters MAF scaling, several issues can occur:
- Lean or rich conditions
- Inconsistent readings
- Overboost
- ECU intervention
- Check engine lights
For me, those outcomes are unacceptable. An intake must improve airflow without introducing calibration instability. That requirement shaped every stage of development and has been met with 100% clean MAF readings, guaranteeing the maximum power output at all rpm’s.
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Hardware Validation on Syvecs ECU
The first validation step was performed on a GR Yaris rally car running a Syvecs ECU configured in "speed density" mode.
This testing environment was useful because no calibration changes were made. The ECU was not compensating for airflow changes via MAF scaling adjustments. Any variation observed would come purely from the hardware.
The intake behaved exactly as intended from a hardware standpoint, confirming the core airflow design before moving into stock ECU validation.
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MAF Verification on Stock ECU & Map
After confirming hardware behavior, the next step was verifying MAF accuracy on completely stock-mapped GR Yaris vehicles.
- Testing was carried out at:
- ACME Motorsport (hub dyno)
- ProfiTuning (MAHA wheel dyno)
The objective was straightforward: reproduce OEM MAF readings precisely.
The result was consistent across vehicles and dyno types. MAF values matched OEM airbox readings on a 1:1 basis. No lean spikes were recorded, no overboost behavior was observed, and no ECU faults were triggered.
Only after confirming this did I consider the intake finalized.
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Dyno Results: Stock Car, Stock ECU & Map
On the ACME Motorsport hub dyno, a completely stock GR Yaris produced 266.4 bhp as baseline.
With the PIRAS Motorsport airbox installed, output increased to 272 bhp, representing a gain of 5.6 bhp.
It is important to interpret this correctly. Below 3000 rpm, dyno variance is inconsistent and not representative. From 3000 rpm onward, the gains are consistent across the curve.
One of the most noticeable improvements is the reduction of the torque dip present in the OEM intake configuration. That dip occurs just before the factory intake flap opens, where airflow momentarily becomes less efficient. With our airbox, that micro-starvation is reduced, smoothing the torque curve.
Above 4500 rpm, the power curve remains consistently higher than baseline.
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Independent MAHA Dyno Testing
ProfiTuning conducted testing on a MAHA wheel dyno with a stock-mapped car equipped with supporting modifications including OPF delete and an intercooler upgrade.
With the airbox installed, the vehicle recorded gains of 17 horsepower and 18 Nm of torque.
It is critical to clarify that this is not an airbox-only gain. In isolation, the expected increase from the airbox alone is in the range of 6–10 horsepower. The higher figure reflects the combined hardware configuration.
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Independent ROTRONICS Dyno Testing
As you may know, it is very tricky to dyno test a stock ECU car while achieving consistent and repeatable results. ACME Racing has a 4wd hub dyno from Rotronics that represents the pinnacle of its sector.
They acquired a huge amount of experience on the GR Yaris while developing the first Syvecs software – on commission to Toyota Italy – while developing the national trophy rally cars, and while helping EcuTek develop their software for this platform, now the market reference software.
They have data stored for any possible tuning and mods configuration, and this resulted in being vital for our development and analysis.
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What Dyno Graphs Do Not Fully Show
Static dyno graphs do not fully capture transient response.
During on-throttle to off-throttle transitions and immediate reapplication of throttle, airflow stabilizes more quickly compared to the OEM airbox. The result is sharper response and more immediate torque delivery.
From a driving perspective, especially in aggressive road or rally-style use, this improvement is noticeable even when peak horsepower gains appear modest.
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Mechanical Refinements in Production
While scaling production, multiple revisions were implemented to ensure mechanical precision and durability.
The rear section geometry was refined, the MAF holder was redesigned for improved accuracy, and the mounting bracket underwent millimeter-level adjustments to improve stability. Larger bolt studs were sourced to improve grommet engagement and reduce movement under load.
These adjustments were made only after repeated physical test-fitting on a GR Yaris with the full production team present. The objective was to eliminate unnecessary movement and ensure consistent long-term fitment.
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Current Production Status (Q1-2026)
The GR Yaris Engine Airbox Intake is now in stock and readily available in quantity.
After the initial production run and refinement process, inventory has been stabilized to support consistent availability and fast shipping.
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Technical Summary
The PIRAS Motorsport GR Yaris Engine Airbox Intake delivers:
- Verified 1:1 MAF scaling compared to OEM
- 6–10 bhp expected gain on a stock vehicle
- Supports total engine power of over 500 bhp
- Reduction of the OEM torque dip
- Stronger high-rpm consistency
- Improved transient throttle response
- No ECU errors or calibration instability
All figures presented are measured across multiple vehicles and dyno types.
. The goal was to engineer a solution that works within factory ECU logic while delivering measurable airflow improvement.
That is what this product achieves, and you can experience the added performance on your GR Yaris! Ready to join the family?