The 2024 Kawasaki KX450 has undergone a ton of changes, one of them requiring an all-new exhaust system. We were eager to develop the best exhaust system possible for the new Green Machine.

Working with multi-time GNCC off-road Champion Steward Baylor we were able to really squeeze every ounce of performance from the new KX. Not only performance but installation on the new KX has been optimized. Working around the new KX chassis we were able to make the new oval-port header fit effortlessly.

Performance gains are massive with our RS-12 Signature Series system, adding a whopping 6.4% max hp and an incredible 13.8% max torque. With gains like this some would think that the new KX would be hard to control, not the case. With the help of our hydroformed oval header, our development team has made the power delivery much smoother than stock!

Our RS-12 muffler has loads of features including our PTF insert system that makes changing inserts a breeze and an optimized muffler shape with added volume and brake caliper clearance. Optional spark arrestor SA-21-K available separately.

Yoshimura's RS-12 systems proudly designed, developed and manufactured in Chino, California.

• Rubber mounted RS-12 muffler dampens vibration to subframe
• Aggressive intelligently designed, the RS-12 asymmetrical shaped muffler allows maximize capacity and incorporates a resonance chamber for managing sound and increasing usable power. RS-12's unique profile also provides more clearance for tire and brake caliper.
• Improved performance gains with refined power delivery.
• Just like the works systems our Factory Racers use, RS-12 systems utilize precision machined joints. Machined joints provide a superior and exacting fit for joints by better securing the seal between two surfaces with a perfect 360 degree contact surface which translates into improved system life, fit and performance.
• New patent pending Precision Taper Fit (PTF) insert ring makes it easy to install and remove sound inserts and spark arresters.
• Works-look matte carbon fiber end cap with industry leading design, innovation and detailing as expected from Yoshimura.
• Carbon end cap covers the RS-12 inner cap, thus improving looks, while providing easier service as compared to other sandwich mounting designs most commonly found in the industry.

UK Delivery Charges

Free delivery on all orders £100 and over*

All orders over £100 are delivered FREE*. All orders from the Mega Motorcycle Store are dispatched using secure couriers, which are fully insured and trackable. All customers receive an online tracking number when their order is dispatched, enabling them to track the location of their delivery online.

*Free Delivery over £100 includes mainland UK only. Excludes Northern Ireland.

UK Delivery Charges

• Orders under £100: £4.99
• 24-hour delivery: £5.99
• Saturday delivery: £14.99
• Orders over £100: FREE 48-hour delivery
• Refund charge: £2.99

Our UK delivery charges apply to remote areas such as Shetland and the Highlands. For all other destinations, please add your items to the shopping cart on the website and calculate the delivery costs to your destination.

UK Delivery Times

Orders must be placed before 1pm for same-day dispatch.

Please allow 1-2 working days for delivery within the UK.

For deliveries outside the UK, please allow 5-7 working days.

Next working day delivery cut-off time is 13:00.

Orders placed on a Bank Holiday will be dispatched on the following working day. Deliveries to Ireland and Scotland may take an extra day depending on your location.

Orders placed on a Saturday or Sunday will be dispatched on the Monday. If you have paid for Next Working Day delivery, your delivery will be due on the Tuesday.

European Delivery Since 1 July 2021, most goods to the EU (including gifts) are now subject to VAT and potentially a clearance fee. The taxes and duties applied depend on the individual contents of the parcel, the weight, and the value. We cannot estimate the costs that may occur and we are not responsible for any fees you may need to pay.

To get a shipping quote for your country, please follow the checkout process and input your delivery address.

Terms and Conditions:

Express delivery applies to mainland UK only and cannot be guaranteed for the Scottish Highlands and other isolated areas. Please contact us if you need further details.