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FMF Racing Factory 4.1 RCT Slip-On

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Product Information

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  • Price Range $374.95 ~ $599.99 Shop Now
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    (17 reviews)

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  • 5

I race a Canadian off-road series that has two simple requirements as it relates to exhaust : 96dB max and spark arrestor, NO EXCEPTIONS! Both of these requirements are hard to meet with the stock Yamaha YZ250FX exhaust, so I starting looking at my options. FMF has been a long-time ThumperTalk sponsor, so naturally I decided to see what they had that might fit the bill. Their stainless steel 4.1 slip-on seemed like a good option, but they were temporarily out. But to my surprise, FMF brought their "A game", offering to kick down one of the premium Titanium versions in exchange for my evaluation. :)

The FMF Ti 4.1 Slip-on for the Yamaha YZ250FX (also fits the YZ250F) is a direct bolt-on replacement for the stock silencer. Outside of being lighter in weight than the stainless option, there are no performance differences between the two. It comes standard with a spark arrestor and wash plug, but the optional quiet core is extra.



Installation is pretty much the same as stock with basic skills & hand tools in about 15 minutes. FMF does recommend a bead of high-temp silicone (not included) where the header and mid-pipe join to insure an air-tight seal. Everything lined up perfectly making for an even easier job. Installing the spark arrestor was a bit confusing at first, but after doing it once, it’s been simple ever since.

The finish of the pipe is a beautiful, raw Ti color. Nothing fancy, anodized, or over-the-top; simple and clean. I noticed no blemishes, burrs, or anything that didn't look well put together, just pure goodness.

Ok, let's get to the good stuff... how does it perform? First, my requirements for racing were met. Out of 5 sound checks, I passed all with ease with one official saying how quiet he thought it sounded. It didn't see how many dB it blew during testing, but passing was my only real concern. While not one of my requirements, a bonus is the weight savings over the stock silencer. The FMF Ti 4.1 slip-on shaves 2lbs. and another pound when running an aftermarket spark arrestor end-cap. The Ti 4.1 also slightly changed my bike's power delivery. A common complaint is that the 250FX is a little aggressive off idle and the Ti 4.1 smoothed that off-idle hit, making the bike a bit more manageable in slippery conditions. It also added a little more over-rev, giving the 250FX a bit more legs in each gear. For my preferences, the added over-rev is great, especially when you need to hold it on just that little bit extra to make that extra pass. I didn't notice any difference in power with the spark arrestor installed.

Pros :thumbsup:

  • Modular spark arrestor.
  • Tested at/below 96dB when racing.
  • Improved bike's power delivery.
  • 2lbs.+ weight savings.

Cons :thumbsdn:

  • Hit to the wallet.

Monk's Bottom-line :prof:
It’s hard to lose with the FMF 4.1 Ti Slip-on exhaust. Not only was it easy to install and fit perfectly, FMF met my requirements when it comes to our racing series. The added weight savings and power gains were equally welcomed. The Ti version exceeded my expectations, but I'm sure that I'd have been equally as pleased with the more budget friendly stainless steel version.

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  • 5

Fits well, light, shorter than the super-long stock muffler

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  • 5

Love my TI version and yes it looks and sound really cool.

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  • 5

I put the Ti 4.1 on my 16 wr450. It's a couple " shorter, sits up behind the # plate a little higher and sounds great. More power at all rpm. I installed the supplied spark arrest screen but removed the piece of metal that's in the middle that you grab on to to remove it. Had the ranger test the Db. It tested at 98db. eBay for 379.99. Free shipping forgot to check prices here on TT.

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  • 5

good tone and no too obnoxious

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