FMF 2009 KX450F Anodized Factory 4.1

FMF
2009 KX450F Anodized Factory 4.1
Complete System With Ti-MegaBomb Header

There are few times I just bolt on an exhaust system and go, "Wow!" But this system on this bike was just like that.

Surely you know the bark of the 2009 KX450F is about as bad and raspy as it gets. Somehow it even fools the sound meter into reading low while sounding way too loud on the track. I've had really good luck in dropping a decibel or two with any FMF MegaBomb header, so I threw on this $849.99 full system during a day of fuel injection testing to see how it would affect the changes we were making. We put the ECU back to stock and then bolted on the pipe, a simple job since the pipe's three segments allow it to slither into place.

Once tightened up, it was on to the track. To the rider the sound is definitely damped, and people trackside also said the bike sounded quieter and better. Our pipe was set up with a 98-decibel tip (or ring, really) installed. Without the ring and running wide-open, the pipe actually makes less power. At the 98-decibel setting the pipe wakes up the KX-F where it is a little sleepy on the very, very bottom, smooths the snappy stock hit zone and has the bike pulling better all the way through the power spread. In fact, it feels like the bike got better traction and used the power better all the time.

We tried to make a better map than stock for this pipe with the FI tuning tool but failed to do so. FMF used the pipe with its 98-decibel insert to make the stock ignition and fuel map work the best it could. We also tried the pipe with the 94-decibel insert (the way we are told all of the pipes will be sold) installed, and there it tests out at just over 96 decibels making it legal for off-road (when you add a spark arrestor, which will quiet it further) and competition-legal for AMA motocross at the pro level.

The bike lost only a little bit of the pickup ferocity, and the perceived sound on the track dropped a little, too-mostly in how far the sound carried. Another good thing about FMF systems: The packing seems to keep working longer than some of the other aftermarket systems out there.

In these sound-conscious times the stock KX450F needs some help. Might as well boost the power at the same time with the FMF system and look cooler by doing it. Just don't run it without an insert installed! -Jimmy Lewis