FMF Fatty Expansion Chamber A42005907000 | KTM Direct

FMF Fatty Expansion Chamber A42005907000

£307.00 In Stock Coming soon
CODE: A42005907000




  • Description
  • Fits
  • Features
  • Shipping and Refund

Unleash the full potential of your KTM motorcycle with the FMF Fatty Expansion Chamber A42005907000. Engineered with extra strong sheet steel, this expansion chamber is built to withstand the demands of intense riding.

The nickel-plated surface not only adds a sleek and durable finish but also enhances the overall performance of your bike. Experience higher maximum power and increased speed as the FMF Fatty Expansion Chamber optimizes the exhaust flow.

Prepare to make a statement with the full sound emitted by this expansion chamber. It adds an aggressive and powerful tone to your motorcycle, making it stand out on the road or track.

The FMF Fatty Expansion Chamber is designed to deliver better power delivery, ensuring that you have the responsiveness and torque needed for exceptional performance. Feel the difference as your bike responds with improved throttle response and acceleration.

For the ultimate performance upgrade, we recommend combining the FMF Fatty Expansion Chamber with a compatible FMF silencer. This combination creates a seamless and perfectly matched system that maximizes power and efficiency.

Upgrade your KTM motorcycle with the FMF Fatty Expansion Chamber A42005907000. Benefit from its extra strong sheet steel construction, nickel-plated surface, higher maximum power, increased speed, full sound, and improved power delivery. Pair it with an FMF silencer for the ultimate performance enhancement. Get ready to dominate the road or track like never before.

Recommended to be used in combination with FMF Titanium Powercore 2.1 Silencer A42005979003

This is compatible with the following KTM motorcycle models:

  • 125 SX 2023-2024
  • Extra strong sheet steel
  • Nickel-plated surface
  • Higher maximum power
  • Higher speed
  • Full sound
  • Better power delivery
  • Combination with FMF silencer recommended

Shipping Information


UK Shipping on orders over £50 (3-5 days delivery): FREE*

UK Shipping on orders under £50 (3-5 days delivery): £3.95

UK Express Delivery (1-3 days delivery): £6.95

Please note that the delivery times above are from the point of dispatch. Whilst many products are available for immediate dispatch, some items have longer lead times as stated on the product page. Be sure to check the expected availability times before ordering.


Custom Charges

If you are ordering goods for delivery outside the UK, please note that your consignment may be subject to import duties and taxes, which are levied once the goods reach the country of destination. Any such charges levied in relation to customs clearance must be paid by you. It is accepted by you that KTM Direct has no control over additional charges in relation to customs clearance. KTM Direct recommends that you check with your local customs officials or post office for more information regarding importation taxes/duties that may be applicable to your online order. You will be the importer of record and responsible for any import VAT and duty that needs to be paid. In addition, any charges for import clearance will be paid by you, the customer. Refunds of any returned order will be of items, not the services incurred.


KTM Direct use Royal Mail for smaller items and DHL for larger items (UK Shipping only)

Royal Mail deliveries are typically sent by Royal Mail 48 so will normally arrive within a maximum of 2-3 working days. DHL deliveries are typically made the next working day, but some remote areas may require an extra day. If your item has not arrived within 5 working days on either service then please contact us by email

All in stock orders placed up until 9.00am are dispatched the same working day. Any in stock orders placed after 9.00am may not be dispatched until the next working day.


Returns Information

We have a 30-day return policy, which means you have 30 days after receiving your item to request a return.

To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.

To start a return, you can contact us at If your return is accepted, we’ll send you instructions on how and where to send your package. Items sent back to us without first requesting a return will not be accepted.

You can always contact us for any return question at

Damages and issues
Please inspect your order upon reception and contact us immediately if the item is defective, damaged or if you receive the wrong item, so that we can evaluate the issue and make it right.

Exceptions / non-returnable items
Certain types of items cannot be returned, like perishable goods (such as food, flowers, or plants), custom products (such as special orders or personalized items), and personal care goods (such as beauty products). We also do not accept returns for hazardous materials, flammable liquids, or gases. Please get in touch if you have questions or concerns about your specific item.

Unfortunately, we cannot accept returns on sale items or gift cards.

The fastest way to ensure you get what you want is to return the item you have, and once the return is accepted, make a separate purchase for the new item.

We will notify you once we’ve received and inspected your return, and let you know if the refund was approved or not. If approved, you’ll be automatically refunded to your original payment method. Please remember it can take some time for your bank or credit card company to process and post the refund too.

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