The FMF Factory 4.1 RCT Stainless Slip-On is built to elevate your Kawasaki KX 450, X, or SR (2019–2023) with noticeable power gains, weight savings, and track-ready tuning features. With FMF’s Resonance Chamber Technology™ and Factory Forward Engineering, it delivers pro-level throttle response and a centralized mass layout to sharpen handling where it counts.
Key Features
Proven Power Gains: Boosts horsepower and torque across the entire RPM range.
RTS Tuning System: Rapid Tuning System makes trackside insert swaps fast and easy.
Crash-Resistant Profile: Compact muffler design reduces vulnerability in the event of a tip-over.
Lightweight Build: Weighs just 7.3 lbs—lighter than stock despite stainless steel midpipe.
Flexible Fitment: Compatible with FMF or OEM headers.
Built in the USA: 100% constructed at FMF’s Southern California factory.
Specifications
Fitment: Kawasaki KX 450 / X / SR (2019–2023)
Item ID: 042369
Type: Slip-On
Construction: Aluminum canister with stainless steel midpipe
Finish: Natural
End Cap: Carbon fiber
Spark Arrestor: Screen insert included
Quiet Insert: 94 dB insert included
Weight: 7.3 lbs.
Use: Closed Course Only
Take your KX to the next level with FMF’s stainless 4.1 RCT—where durability meets factory-built performance.
Shipping Information
We strive to get your order to you as quickly as possible! Here’s what you need to know about our shipping policies:
Fast Shipping: Most items ship within the same day or within 48 hours of your order being placed.
Custom Orders: Please allow additional processing time for custom or made-to-order products.
Flat Rate Shipping: Enjoy $9 Flat Rate Shipping on all standard orders.
Free Shipping:
Orders over $90 qualify for FREE shipping!
Always FREE shipping on:
ASV Levers
Rough Country Products
S3 Power Sports Products
No Sales Tax Outside Minnesota: Since we only have a tax nexus in Minnesota, sales tax is only collected on orders shipped within MN.
Customers with shipping addresses outside Minnesota automatically save on sales tax—just one more way to get great value!
(Please consult your local tax policies for compliance in your area.)
We’re committed to delivering your products efficiently and reliably. Thank you for choosing us!
Let customers speak for us
from 12 reviews
Great service
Was looking for the limited addition new glory harnesses and sent a message to make sure they had them in stock. Got a quick response and went ahead and ordered he shipped them out next day. Super happy with the service.
Excellent service and reached out to make sure I got what I needed. Got the lever in under a week here in Kentucky. Actually ordered another for another bike because of service.
I was really hoping for this lever to help my 4 year old on his stacyc and it made a huge difference. Closer to the bars, easier for him to squeeze as he is 4 and all around great lever. Super happy with the purchase.
