KTM 450 SX-F Factory Edition

Our KTM 450 SX-F Factory Edition test bike is an amazing machine that outperforms every KTM we’ve ever ridden. The FMF Factory 4.1 exhaust makes it even better.

2015 KTM 450 SX-F Factory Edition | FMF Factory 4.1 Test

We’ve been riding and racing our 2015 KTM 450 SX-F Factory Edition test bike for several weeks now, and to say that we are impressed with the machine would be an understatement. While you’ll have to wait for the full test feature in the May issue of TransWorld Motocross, we will say that the powerband is one of the smoothest, yet strongest, we’ve ever enjoyed on a bone-stock machine.

As always, Don Emler and his crew at FMF are obsessed with making a good thing great, and we hadn’t had our bike more than a few weeks before Donnie Emler, Jr. phoned us to see if we wanted to test the Factory 4.1 System they had developed for the KTM Powerparts Catalog. Well, you don’t have to ask us twice if we want to try out something new and shiny, and a few days later we met Little D at Zaca Station MX in Los Olivos, California, for a day of motos.

With the stock exhaust in place, the 450 SX-F FE has a remarkably smooth powerband that is deceivingly powerful. Even with the dual-map switch set in the more aggressive setting, the FE has great roll-on throttle response and a smooth surge of power that pulls well into the upper RPM range. While the bike has no real arm-jerking hit, it is never at a shortage for power and twisting the throttle results in instant results. With such a broad, easy to control style of power, we were honestly hesitant to mess with a good thing by installing an aftermarket exhaust.

FMF Factory 4.1

The FMF Factory 4.1 for the 2015 KTM 450 SX-F Factory Edition weighs in 2.6 pounds lighter than the stock exhaust system.

After riding a couple motos at Zaca with the stock exhaust in place, Little D and I set out to install the FMF Factory 4.1 system. Removing the stock header proved to be a nightmare, as the one-piece header and mid-pipe will not slide out between the frame and rear shock. After numerous attempts to jiggle the pipe free, we finally relented and removed both the top and bottom shock mount bolts, so that the shock could be moved to the side to allow removal of the stock header. Compared to the nightmare that removing the stock system was, the FMF exhaust practically installed itself. All jokes aside, the system did fit perfectly and can be both installed and removed with out touching the shock mounts. In our bare hands, the weight difference between the stock and aftermarket systems was quite noticeable. A little investigation work later in the week with some scales revealed that the Factory 4.1 system weighed 2.6 pounds less. On a bike that is already feathery light, saving an additional 2.6 pounds is huge!

Donnie Emler, Jr. puts out KTM 450 SX-F Factory Edition though it's paces.

Donnie Emler, Jr. puts out KTM 450 SX-F Factory Edition though it’s paces.

On the track, the power gains were immediately noticeable. While the bike lost a tiny bit of its roll-on power, it was replaced with a much more exciting punch down low that pulled hard into the middle of the powerband, where things really began to get interesting. So beefy is the mid-range power with the Factory 4.1 system installed, that it was possible to ride the entire Zaca Station track in third and fourth gears. The bike still pulls well into the upper RPM range with authority, but the upper low-end and mid-range power is so impressive with the FMF exhaust installed, that we rarely revved it out.

To be honest, we weren’t sure at first if we really preferred the feel of the powerband better with the FMF system installed, as it made the Factory Edition bike feel racier and more aggressive. After swapping back to the stock system (yes, we removed the shock bolts to do so), it was easy to see that the more aggressive powerband yielded by the FMF exhaust was not only more exciting to ride, but more effective, as well.

If you are one of the lucky few who got their names on the short list to get one of the 2015 KTM 450 SX-F Factory Edition bikes, trust us: the bike is hands-down the best bike KTM has ever produced, but the crew at FMF Racing can make it even better.

The Factory 4.1 Exhaust systems by FMF are available exclusively through the KTM Powerparts dealers for $999.00