Before You Buy an FMF Exhaust - Check This Out!

A #test between a stock 2022 #yamaha #yz450f exhaust and a #FMF 4.1 slip on exhaust. Sound comparison on and off the track, and my breakdown of the differences I saw and felt after riding months with the stock exhaust. My initial thought after riding a couple sessions with the FMF 4.1 is at the end of the video. Half way through There’s a back to back comparison on each of the test so I did.
FMF Description:

The Factory 4.1 RCT incorporates the latest in FMF Resonance Chamber Technology™ both internally and externally. In addition, we achieve a shorter overall length that is less susceptible to crash damage and complementary to our Factory Forward Engineering - moving the muffler closer to the motor to centralize mass. The Factory 4.1 RCT is constructed from only aerospace grade materials that meet our exacting specifications and is manufactured 100% at our Southern California factory.

-Available in Natural Aluminum Muffler with Carbon End Cap

-Massive Power gains throughout the RPM range.

-Huge weight savings

-New RTS (Rapid Tuning System)

-FMF uses the highest quality proprietary blend of alloy grade titanium made especially to our standards.

#dirtbike
#motocross
#supercross
#bikebuild
#450f
#dirtbikeexhaust

[ivorscruton]

Far to many people think that slapping on an aftermarket exhaust will immediately increase performance, this is actually not the case. To achieve more power, adjusting the fuel delivery map is usually required, especially on street legal machines, due to the lean mixture needed to meet emission standards. Without a dyno, this is extremely difficult, as its next to impossible to know how the engine responds to the changes and can actually cause damage due to exhaust gas temperature increases.The ear and ass dyno is an extremely misleading.

[jeffholcomb]

I have a 22 yz450f and looking at adding an exhaust myself. What you said is exactly what I was looking for. I was wanting more linear power and also wanting to be able to run 3rd gear a little better.
Also glad you touched on the sprocket, because I was looking at going to a 50t but you said you may go back down to a 49t.
I’m an older rider and looking to help be smoother in the corners to keep from wearing me out so bad.
Thanks for the review!

[jg]

Good review - thanks. How would FMF sound & feel with spark arrester? Supposedly you will have less low end loss compared to not running it & will be quieter.

[terryrasor]

So what would be the first thing you’d get if not a slip on? (it’s what you said at the end)

[damonforrest]

That thing you pulled out of the muffler did you leave that out? Sorry for the ignorance, but when I saw you pull it out and I didn’t see you reinstall it. I had to ask the question. Hope you don’t mind.

[Mattsjeeprubicon]

I have a 23 yz450 fx i was looking at the fmf slip on vs the full exhaust. How do you get it mapped right with the exhaust. If you have a street bike. Ive got an R1 and when you do exhaust youve got to have it remapped. On the power tuner app it doesnt have any maps for modified exhaust or any suggestion on where to adjust.

[saulobrien]

How do you stop the exhaust leak around stock header

[eddiepwilliams]

Dammn I get hard listening to this beauty🥰

[boomcity]

Riding off rode without a spark arrestor is foolish and moronic. I see fires every year caused by stupid morons.