Features
Valve-less, Dual Tail Tip Layout: This exhaust system features a valve-less design and dual tail tip layout. The large-diameter titanium slash tailpipe creates a commanding rear view, leaving a strong impression compared to the stock exhaust.

Sturdy and Aesthetic Bracket Placement: Brackets connecting the left and right silencers are positioned at the center notch and feature the HKS logo, ensuring both visual appeal and structural integrity.

Includes "EXHAUST ERROR CANCELLER": HKS provide an "EXHAUST ERROR CANCELLER" to
prevent error codes when the valve is not in use, allowing for a worry-free experience.

Smooth and Enjoyable Driving: Experience a comfortable and noise-free ride at low revs. The overall sound quality is robust, delivering a deep bass sound that intensifies as the revs increase, providing a powerful auditory experience

Certification No.	JQR30232128
Main Material	SUS304
Outer Tail Diameter	φ119
Main Pipe Diameter	φ74.7→φ60.5×2
Close Noise Level (Factory)	88/88dB (Idle：70/70dB）
Close Noise Level (HKS)	91/90dB (Idle：71/70dB)
Exhaust Pipe Minimum Ground Clearance	135mm
Exhaust Pipe Minimum Ground Clearance	Exhaust mid pipe

Product features
The tail features a powerful φ119 titanium tail with two left and right-hand tailpipes, creating a seamless and bulb-less layout.

A bracket is expertly positioned at the factory center tail section, with the HKS logo laser engraved for added aesthetics. The HKS logo is visible from the bumper notch in the rear view, showcasing the installation of the HKS exhaust.

While the stock exhaust valve opens to reduce exhaust resistance at high RPM, this product is valve-less and incorporates a straight structure inside the silencer, resulting in a 40% reduction in exhaust resistance compared to the stock valve when open.

We've achieved precise control of sound volume through meticulous sound engineering. Even without valve-less valves, there is no muffled sound in the mid-range RPM range, providing a comfortable driving experience. Enjoy a sporty sound throughout the entire RPM range, from low to high revs.

To avoid any issues related to valve-less operation, we provide the "EXHAUST ERROR CANCELER" with your purchase. This ensures a stress-free and worry-free driving experience.

Advantages of installing HKS LEGAMAX Sports
The two-piston layout has been meticulously designed to maintain low exhaust pressure across all engine speeds.
In the low and mid-range of the engine, where the valves close in the stock setup, you can revel in a robust sports sound without any unwanted muffled noise!

Comparison with a stock
The tail is three-pronged, with an exhaust switch
valve in front of the center tail.

Main purpose of stock valve
Stationary - low speed
⇒Valve is open
Low to medium rpm range
⇒Closing the valves to improve the quietness of the vehicle interior
High rpm range
⇒Open valves for low exhaust pressure and sports sound

Flow rate
Stock - Valve Closed: This setting secures the valve on the stock muffler in the closed position.
Stock - Valve Open: This setting fixes the valve in the open position on the stock muffler.
HKS: LEGAMAX Sports 31021-AT009 (this product）

The graph above illustrates the relationship between flow rate and pressure, as measured on a flow bench. Lower pressure relative to flow rate indicates reduced resistance. At a flow rate of 200 L/s, the respective pressures are as follows:
Stock - Valve Closed: 9.3 kPa
Stock - Valve Open: 5.1 kPa

These results demonstrate that compared to the closed valve and this product, pressure is reduced by 68%, even when the valve is open, a 41% reduction in pressure is achieved. This reduction is attributed to the pipe diameter, layout, and internal structure of the silencer, which collectively contribute to significantly lowering exhaust pressure

EXHAUST ERROR CANCELER

Regarding the genuine muffler's exhaust switch valve, the manufacturer's website defines its
purpose as follows:
Achieving low exhaust pressure at high engine speeds.
Delivering a sporty sound when the valve is open.
Ensuring comfortable cruising at low and medium engine speeds.

These functions are carried out through the motor-controlled operation of the valves.
If the valve is not used when installing this product, the following situations may occur:
1. If the coupler is left disconnected: An error code will occur.
2. If the entire motor for the valve is disconnected from the genuine muffler during idling condition: An error code will occur.

In both cases, the check engine lamp may not illuminate, but a record of disconnection or motor abnormality will be stored. To identify and diagnose these errors, it is necessary to use an OBD2 diagnostics machine.

As OBD vehicle inspections are set to commence, there is still a concern about the possibility of error codes being triggered.

Therefore...
An "EXHAUST ERROR CANCELLER" is included!

The "EXHAUST ERROR CANCELER" is an electrical component designed to prevent errors related to the exhaust system. When connected, it ensures that no error codes are recorded, and no warning check engine lamps are illuminated. This part is designed based on the manufacturer's error countermeasure information, and its installation will not cause any issues with the vehicle.

By implementing measures to address error codes, which are a concern when the valve is not used, this product provides a stress-free and safe solution for your vehicle's exhaust system. It effectively prevents errors and maintains the smooth operation of your vehicle.

The provided graphs and figures are based on in-house measurements and are subject to variation depending on the specific vehicle and measuring equipment used. Actual results may differ based on individual vehicle characteristics and the type of measuring equipment utilized

The installation of the muffler has proven effective in enhancing power and torque in the mid-range RPMs.

The output has increased by up to 4.0%, while torque has seen an improvement of up to 5.2%. This reflects the positive impact of the muffler on the vehicle's performance within that RPM range

HKS vs stock

Maximum output

(kW/rpm)

Max. torque

(Nm/rpm)

HKS 31021-AT009

221.6/6600

431.0/4250

Stock

221.2/6600

414.8/4300

Maximum power and torque difference

Output	7.7kW (10.5PS)	/4650rpm	⇒ Up by approx. 4.0%
Torque	18.9Nm(1.9kgf・m)	/3200rpm	⇒ Up by approx. 5.2%

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Collection: 2023+ Toyota GR Corolla Exhaust

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