Milltek Exhaust System for Toyota GR Yaris (Gen 2) SSXTY243

The Milltek Sport SSXTY243 is a GPF/OPF-back performance exhaust designed for the 2024-onwards Toyota GR Yaris Gen 2.

Its main engineering feature is an electronically controlled exhaust valve that changes the exhaust flow and sound character according to vehicle speed and engine RPM.

1. Technical specifications

Specification	Details
Manufacturer	Milltek Sport
Part number	SSXTY243
Vehicle	Toyota GR Yaris Gen 2
Engine	G16E-GTS 1.6L Turbo
Application	2024 onwards, GPF/OPF models
Exhaust diameter	76.2 mm (3 inches)
Construction	Stainless steel
Configuration	GPF-back
Exhaust valve	Electronic CANBUS
Exhaust tips	2 × 115 mm GT polished
Homologation	ECE marked
Race system	No

2. Understanding its engineering

The SSXTY243 consists of five major components:

Component	Function
MSTY145REP	Centre silencer bypass
MSVCTRL15	CANBUS valve control module
MSTY177	Valved rear silencer
MSTY178	Left-side outlet pipe
MSTY179	Right-side valved outlet pipe

The interesting part is the valve technology.

Milltek uses vehicle CANBUS data to determine when the exhaust valve opens or closes.

• Normal cruising: valve remains closed.
• Above approximately 80 km/h: valve opens.
• Above approximately 4,500 RPM: valve opens.

When open, the exhaust takes a less-restricted route through the rear silencer arrangement, creating a more pronounced exhaust sound.

3. Why the 3-inch diameter matters

A 76.2 mm exhaust pipe offers substantial flow capacity.

Potential engineering benefits:

• Reduced restriction in the exhaust section being replaced.
• Better flow capacity under higher exhaust mass-flow conditions.
• Greater flexibility for future engine upgrades.
• More distinctive exhaust acoustics.

However, bigger piping does not automatically produce more horsepower.

Actual power gains depend on turbocharger characteristics, backpressure, exhaust temperature, engine calibration and the original exhaust configuration.

4. Advantages and disadvantages

Advantages	Disadvantages
ECE-marked system	Premium aftermarket pricing
Electronic exhaust valve	No standard manual valve control
3-inch piping	Does not replace the downpipe
Polished 115 mm tips	Larger tips may not suit everyone’s taste
Vehicle-specific Gen 2 fitment	Requires correct GPF/OPF compatibility
Retains factory particulate filter	Power gains are not guaranteed

Important: The standard SSXTY243 valve cannot be manually opened or closed on demand. Milltek identifies optional supporting controllers, but adding manual override removes its ECE approval status.

5. Technical verdict

Sound engineering- Strong concept

Flow capacity- 3-inch

Daily usability- Good design

Power improvement- Not quantified

The SSXTY243 is primarily a sound-character and exhaust-flow upgrade rather than a guaranteed horsepower modification.

Its most attractive engineering feature is the combination of a centre silencer bypass, valved rear silencer and CANBUS-controlled operation.

For a Gen 2 GR Yaris owner, the important consideration is whether the priority is sound refinement, exhaust flow or measurable engine performance.

Milltek Exhaust System for Toyota GR Yaris (Gen 2) SSXTY243