Ranking Every Toyota GR Yaris Mod From Best to Worst

The Toyota GR Yaris arrived in 2020 as a homologation special for Toyota's WRC efforts, packing a turbocharged 1.6-liter three-cylinder engine with 268 horsepower and an advanced all-wheel-drive system. Unlike many modern performance cars that come heavily restricted from the factory, the GR Yaris is remarkably well-sorted but responds exceptionally well to strategic modifications.

Quick Navigation

• Quick Answer
• Key Takeaways
• S-Tier: The Essential Three
• A-Tier: Strong Upgrades with Trade-offs
• B-Tier: Worthwhile for Specific Goals
• C-Tier: Low Priority Modifications
• D/F-Tier: Modifications to Avoid
• Build Stage Roadmap
• Bottom Line

Quick Answer

The best GR Yaris modifications in order: ECU tune ($800-1,500), high-flow air filter ($60-150), and intercooler upgrade ($800-1,800). These three deliver the biggest performance gains while maintaining reliability. Avoid cheap coilovers and turbo upgrades without supporting modifications—they'll hurt more than help.

Key Takeaways

• Stage 1 ECU tune delivers 25-40 horsepower gains for under $1,500—the single best performance modification
• Factory suspension is excellent—only upgrade to quality coilovers if you need adjustability
• Three-cylinder engine responds exceptionally well to increased boost pressure and timing adjustments
• Modification order matters—poor choices can upset the car's inherent balance
• Budget $1,660-3,450 for the essential trio of air filter, tune, and intercooler

S-Tier: The Essential Three

ECU Tune - The Ultimate Bang for Buck

Price: $800-1,500 | Gain: 25-40 hp, 30-50 lb-ft torque

The ECU tune represents the single best performance modification for the GR Yaris. Toyota's conservative factory tune leaves significant power on the table. Reputable tuners like Revo, Mountune, and various local specialists safely extract additional power while maintaining reliability.

Stage 1 tunes typically raise power from 268hp to 295-310hp, with torque increases from 273 lb-ft to 300-320 lb-ft. The three-cylinder engine responds exceptionally well to increased boost pressure and timing adjustments. Most owners report improved throttle response and more linear power delivery alongside the raw power gains.

High-Flow Air Filter - The Foundation

Price: $60-150 | Gain: 3-8 hp (more with tune)

A high-flow air filter from K&N, BMC, or Green Filter provides the foundation for other modifications while offering immediate benefits. The stock airbox design is actually quite good, but the paper filter element restricts flow.

This modification works synergistically with ECU tuning, allowing tuners to take advantage of improved airflow. The performance gain alone is modest, but the low cost and easy installation make it essential for any build path.

Intercooler Upgrade - Heat Management

Price: $800-1,800 | Gain: Maintains power in hot conditions, enables higher boost

The factory intercooler becomes a limiting factor in hot weather or extended track sessions. Upgraded intercoolers from Mishimoto, Wagner Tuning, or Process West significantly improve heat rejection and allow for more aggressive tuning.

Temperature improvements of 30-50°F are common, translating to consistent power delivery and reduced risk of heat-related power loss. Installation requires front bumper removal but enables Stage 2+ tuning.

A-Tier: Strong Upgrades with Trade-offs

Downpipe Upgrade

Price: $600-1,200 | Gain: 15-25 hp (with tune)

A high-flow downpipe reduces exhaust back-pressure and enables more aggressive tuning. Options range from catted versions maintaining emissions compliance to catless designs offering maximum flow but potential legal concerns.

The modification requires ECU tuning to realize benefits and noticeably increases sound levels. Professional installation is recommended due to the confined workspace.

Coilover Suspension

Price: $1,200-3,500 | Gain: Improved handling precision, adjustability

Quality coilovers from KW, Ohlins, or Bilstein offer improved handling precision and adjustability over the already-excellent stock suspension. The main benefits include adjustable ride height, damping control, and improved track performance.

Daily comfort typically suffers, and the high cost requires careful consideration of intended use. This modification is more about fine-tuning than correcting deficiencies.

Limited Slip Differential Upgrades

Price: $1,500-4,000 | Gain: Improved traction and handling balance

The GR Yaris's Torsen center differential and open front/rear differentials can be improved with aftermarket LSD units from Quaife, Wavetrac, and OS Giken.

These modifications dramatically improve traction and handling balance, particularly on track. However, high cost and installation complexity limit their appeal for street-focused builds.

B-Tier: Worthwhile for Specific Goals

Cat-Back Exhaust System

Price: $800-2,000 | Gain: 5-12 hp, improved sound

Cat-back systems from Milltek, Borla, or HKS provide modest performance gains with significant sound enhancement. The three-cylinder engine's unique character responds well to quality exhaust tuning.

Performance gains are modest without additional modifications, making this primarily an aesthetic upgrade. Sound levels vary dramatically between manufacturers.

Short Shifter Kit

Price: $200-500 | Gain: Improved shift feel and speed

Short shifter kits reduce throw length and improve shift precision in the six-speed manual transmission. The modification improves driver engagement and can reduce shift times, but benefits are subjective.

Brake Pad Upgrade

Price: $150-400 | Gain: Improved stopping power and fade resistance

Performance brake pads from Hawk, StopTech, or Endless provide improved stopping power and fade resistance over stock pads. The Brembo brake system responds well to pad upgrades.

Street-oriented pads offer better initial bite without compromising daily drivability. Track-focused pads provide superior performance but may require warm-up.

C-Tier: Low Priority Modifications

Cold Air Intake System

Price: $300-800 | Gain: 0-5 hp (often none)

Complete cold air intake systems often provide minimal performance gains over a high-flow filter in the stock airbox. The GR Yaris's factory intake design is well-executed, making wholesale replacement unnecessary.

These systems primarily offer aesthetic appeal and enhanced intake sound. Some designs may actually reduce performance due to heat soak.

Blow-Off Valve Upgrade

Price: $200-500 | Gain: Minimal to none

Aftermarket blow-off valves from HKS, Turbosmart, or Forge provide enhanced sound but minimal performance benefit. The primary benefit is audible enhancement with the characteristic "whoosh" sound on throttle lift.

Aesthetic Modifications

Price: $200-2,000 | Gain: Minimal at street speeds

Aerodynamic additions like rear spoilers, front splitters, and canards from Maxton Design provide minimal benefit at street speeds but enhance appearance. These modifications primarily serve aesthetic purposes unless the car sees regular high-speed track use.

D/F-Tier: Modifications to Avoid

Cheap Coilovers

Price: $400-800 | Performance: Often negative

Budget coilover systems from unknown manufacturers often provide worse performance than stock suspension while compromising ride quality and reliability. The GR Yaris's factory suspension is quite good, making cheap replacements a significant downgrade.

Turbo Upgrade Without Supporting Modifications

Price: $3,000-8,000 | Risk: High reliability issues

Turbo upgrades without proper supporting modifications often result in unreliable power gains and potential engine damage. The stock turbo responds well to tuning and provides adequate performance for most users.

Engine Internals for Street Use

Price: $5,000-15,000 | Necessity: Unnecessary for most applications

Forged pistons, rods, and other internal modifications are overkill for most GR Yaris applications. The stock engine handles Stage 2+ tuning reliably, making internals worthwhile only for extreme power goals exceeding 400+ horsepower.

Build Stage Roadmap

Best First Three Modifications ($1,660-3,450):

• High-flow air filter ($60-150)
• ECU tune ($800-1,500)
• Intercooler upgrade ($800-1,800)

Best $3,000 Path:

Add downpipe upgrade ($600-1,200) and performance brake pads ($150-400) to the essential trio for Stage 2 tuning capability.

Best Track Path:

Prioritize ECU tune with supporting mods, then coilover suspension ($1,200-3,500) and LSD upgrades ($1,500-4,000) for maximum handling precision.

Best Street/Show Path:

Start with ECU tune, add cat-back exhaust ($800-2,000) for sound enhancement, then aesthetic modifications ($500-2,000) for visual impact.

Bottom Line

The Toyota GR Yaris responds exceptionally well to modifications when applied in the proper sequence. Start with the essential trio of high-flow air filter, ECU tune, and intercooler upgrade for maximum performance per dollar. Avoid cheap alternatives and unnecessary complexity—the platform's inherent balance rewards quality over quantity. Focus your budget on proven modifications from reputable manufacturers, and you'll unlock substantial performance gains while maintaining the reliability that makes the GR Yaris special.