Yamaha’s Raptor 700 is one of our favorite stablemates, as it’s fast, comfortable and will go just about anywhere. We have a lot of seat time invested in the Raptor over the years, and many of those riding hours have been on built machines—big-bore kits, stroker motors, turbocharged builds—you name it, we’ve tested it. But for average owners who don’t want to spend the same amount they paid for their Raptor on engine work, what else is there?

Exhaust systems are usually the first performance product ATV riders go for. We hate to say it, but most riders just like their machine to be loud. We are quite the opposite, however; if we have to choose between an extra couple horsepower or having a quiet pipe, we will take the latter every time. Quiet pipes keep riding areas open longer, as nosey neighbors don’t fuss when they can’t hear something to complain about. If the guy in the apartment next to you clashed the cymbals on his drum kit every day while you were trying to relax, you would get annoyed too.

We are behind the AMA’s noise-regulation changes, and we want to see every aftermarket pipe hit the 94 dB limit. Around 94 dB is a good mix between a loud, aggressive sound and respectful, responsible riding. Enter FMF’s Factory 4.1 exhaust system for the Raptor 700—it’s a way to get quite a bit more power without ruining your riding territory. The FMF quiet insert must be purchased separately, as the slip-on system does not come with the 94 dB insert—it’s $29.99.
Built from stainless billet aluminum, and titanium, the Factory 4.1 is about as exotic as a production exhaust system gets. The muffler hanger is machined from beautiful billet aluminum, as is the end-cap insert. The muffler end cap and body are titanium, with a stainless steel perforated core and mid-pipe. The slip-on system will cost you $399.99, and it’s the last one you’ll ever have to buy, as FMF products are built tough with high-quality materials. In recent testing, we have yet to get one to fail.

Installation is simple: unclamp the stock exhaust at the mid-pipe, unbolt the muffler, and pull the old, heavy restrictive muffler off of the Raptor. The new FMF muffler weighs about half as much as the stock unit and produces a ton more power from bottom to top. We chose to use a slip-on system, because on the dyno, an aftermarket head pipe only makes 1–2 horsepower more on a stock motor than the stock head pipe does. The slip-on is more cost-efficient and allows you to retain the stock heat shield, which is a big plus.

In conjunction with the FMF pipe, we installed their fuel tuner, which is a plug-and-play-type device that comes pre-mapped for their exhaust system. We pulled the airbox lid and ran it with a K&N filter.


With the FMF pipe and quiet insert installed, the exhaust note of the Raptor is much more enjoyable than stock. Throttle response feels more healthy, and the Raptor no longer sounds like the world’s angriest bullfrog. It pulls harder from the bottom up, but you feel the biggest difference from mid to top. The Raptor’s already-impressive midrange power now feels even meatier, and it hangs on longer than stock. Expect a healthy 6–8 horsepower increase at peak and even more of an increase at the top of the rev range, with a good  torque boost in the midrange, too.


The FMF Factory 4.1 exhaust is beautiful, well designed, durable and makes a big performance gain. You can’t go wrong, especially for $430 (the exhaust system without the insert is $399.99). If you keep the stock airbox lid on, you can even run the pipe without a tuner—although it will run stronger and cleaner if you utilize FMF’s $264.95 Power Programmer, which also allows you to fine-tune the EFI map with three buttons. Contact FMF Racing at (310) 631-4363 or visit www.fmfracing.com.

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