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FMF Factory 4.1 Dual RCT Complete Exhaust W/ Stainless Megabomb
FMF Factory 4.1 Dual RCT Complete Exhaust W/ Stainless Megabomb

$877.99 - $1169.99
10% Off - Save up to $130.00

Item #FMF000U

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7 Reviews
5 out of 5 stars
5 Star   7 4 Star   0 3 Star   0 2 Star   0 1 Star   0
All Reviews
Keyon888 Verified Purchaser
Over 10 months ago Ca
Awesome exhaust for my 2017 Crf450r

This is a great exhaust system, built to perfection and super easy to install! Made the bike sound deeper and the carbon fiber looks sweet! Highly recommend this system

Rhodes406 Verified Purchaser Top 1000
1 year 2 months ago Estill, SC
Great fit n sound

Purchased these as I have had prior FMF exhaust. As expected sounds great along with look sharp. Welds are good and clean. Pleased with them

Jut b Verified Purchaser
1 year 4 months ago Clarklake, Mi
All around worth the money

I purchased this set for my 2017 Crf250 and they sound great! Installation was super quick and easy and has that great throaty low end sound I was looking for. Easily the loudest exhaust I’ve ever personally owned with the spark arrestors out. I will say with the Quiet core spark arrestors in I did lose quite a bit of top end but that was expected. Best purchase I’ve made for my bike by far!

1 year 6 months ago Cassville, MO 65625, USA
Great sound

2017 crf 450RX. After install I noticed a smoother low end throttle response. Bike didn’t seem as jerky. They also have a great throaty sound. The stock set up was too raspy for me.

2 years 3 months ago Monroe, MI, USA
Fmf mega bomb header

this exhaust is great i love the sound of it and how much better my bike performs at races i would recound this to everyone that asked how i like this prodest

Over 5 years ago Montana, USA
Love the new sound!

Installed this on my 2013 CRF450R as I wanted to keep the dual exhaust because it looks incredible and sounds even better. Louder than stock without the spark arrestors and that is exactly what I wanted. I removed the air filter screen and then had the local shop remap the ECU . It feels like a big increase in power but some of that may be just the great sounding motor.

Over 6 years ago California
Great exhaust system!

This exhaust was the missing link on my 2013 CRF 450R. It made it more snappier and helped the bike pull better instead of flattening out. When I rode with it for the first time I knew immediatley my bike responded better.

6 Questions
Answered:   6
Not Yet:   0
matt a
Q: Is the fmf 4.1 fim and ama approved? what is the diameter of the screen opening? i need to be at or under 0.023. thanks
Over 6 months ago
Top 10
Over 6 months ago
A: The FMF Factory 4.1 Dual RCT Complete Exhaust W/ Stainless Megabomb is approved by the AMA. FMF does not have an FIM approval, but the AMA requirements are the same as the FIM.

To help us to find the correct parts, we will need to know the year, make, and model of your motorcycle.
Depending on the bike for which it is intended, the rear opening of the FMF 4.1 muffler can be between 1 1/4" to 1 5/8" / or 31.75mm to 41.275mm.

I regret that I don't know if the number 0.023 you referred to is inches, feet, millimeters, centimeters or a meter. 0.023 if an inch is less than the thickness of a sheet of paper. 0.023 of a millimeter is less than the thickness of a hair. 0.023 of a meter, or 2.3 centimeters, is less than one inch.
Q: Mapping
1 year 11 months ago
I'm interested in installing this system on my 2017 cry 450r, will I have to get the ecm remapped to run properly? Worried about a lean running bike and deceleration backfire along with higher cylinder temp, burnt valves
Top 25
1 year 11 months ago
A: Fuel injected bikes will still run properly and see some of the available benefit after installing an exhaust system on them. If you want to get the most power and benefit from the exhaust system (and other motor upgrades) it is always recommended to get a tuning tool and remap the ECU.
Q: Does it fit on a 2015 raptor 700r se or is their any full exhust systems for this year and model atv
Over 4 years ago
Top 10
Over 4 years ago
A: No, this FMF system is for dirt bikes. We have HMF, Yoshimura and Big Gun available for your Raptor 700.

Just be sure to correctly select the Year/Make/Model of your ATV before ordering so we can be sure to send you the correct product for your ATV. Also, feel free to give us a call at 888-676-8853 and we would be happy to help you out with your order.
Q: Does this system (FMF Factory 4.1 RCT Complete Exhaust With Stainless Megabomb Header - Dual) come with spark arrestors?
Over 5 years ago
MotoSport Staff
Over 5 years ago
A: Yes, spark arrestor screens are included.
Q: What is the db measured at without the quiet insert? is it difficult to remove?
Over 6 years ago
MotoSport Staff
Over 6 years ago
A: This will be a 98 dB system without the quit core installed and a 94 dB system with it installed. The quite cores are held in with one bolt on the bottom of the exhaust tip. Very quick and easy installation and removal.
Q: How easy is it to remove the spark arrester? Do I need to drill out rivets or is it as easy as unscrewing a screw?
Over 6 years ago
MotoSport Staff
Over 6 years ago
A: There will be no drilling required to remove the spark arrestor screens. A single screw is all that holds them in.

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See Fitments
# Part Numbers
Product Variant Manufacturer Part #
Aluminum 041531
Titanium 041551
California Proposition 65

WARNING: This product contains chemicals known to the State of California to cause cancer, and birth defects or other reproductive harm. Wash hands after handling. For more information, go to