January 20, 2012
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WHAT IS IT? It’s the latest version of FMF’s premium race exhaust system for the new 2012 electric-start KTM 250SXF?a bike that needs horsepower help.

WHAT’S IT COST? $899.99 (full system with MegaBomb).

CONTACT? or (310) 631-4363.

WHAT STANDS OUT? Here’s a list of things that stand out with FMF’s KTM 250SXF Factory 4.1 exhaust.

(1) Updates. FMF has recently made some improvements to their Factory 4.1 systems. Thanks to the gained experience with their RCT (Resonance Chamber Technology), they have figured out how to tweak the shape to optimize exhaust gas pressure to get the best balance of noise and performance levels. Additionally, the muffler canister has greater volume and more muffler packing. The stinger has a circlip holding it on instead of a bolt, and the muffler mount has been beefed up for strength. Overall, FMF has tried to lower the decibels without losing any power.

(2) Performance. In stock trim, the 2012 KTM 250SXF powerband leaves a lot to be desired. It needs more peak power, more hit and faster rev. The FMF Factory 4.1 system pumped up the power off the bottom. but made its biggest improvement in the midrange. As an added plus, the FMF pipe pulled harder than the stock KTM exhaust on top, but it didn’t rev any higher.

(3) Head pipes.
Given their druthers, FMF prefers to showcase their MegaBomb head pipe over their PowerBomb. We tested both head pipes to see what our preferences were. On the 2012 KTM 250SXF, every MXA test rider elected to race with the PowerBomb head pipe. That’s not to say that the MegaBomb didn’t work, but we preferred the peppier, freer-revving and high-rpm feel of the PowerBomb over the MegaBomb’s better grunt and low-end power.

(4) Wrenching. Testing KTM pipes is a chore because you can’t get the stock pipe off without unbolting the shock first (and since we switched back and forth between the stock and FMF pipes several times for each test rider?we were hating life). Installing and removing the FMF 4.1 exhaust system was much easier because it is a three-piece design that didn’t require us to disassemble the 250SXF.

(5) Fit. The FMF pipe slipped right in place, and we didn’t have to unbolt the midpipe to swap back and forth between the PowerBomb and MegaBomb head pipes. For longer-term maintenance, there are four screws at the front end of the muffler canister that let you slide it off for repacking.

(6) Options. You can order a natural metallic or blue anodized muffler, along with an optional carbon fiber end cap, for an extra $50. You can also outfit the muffler with a MegaBomb ($499.99), PowerBomb ($349.99) or stock header/midpipe. FMF’s Quiet Core 94dB insert is included.

We have two quibbles: (1) It is hard for an exhaust pipe to change the personality of a slow machine. We’d hazard a guess that the KTM 250SXF’s slowness issues lie in its ignition mapping and cams. An exhaust pipe is the first step on getting the power up to snuff, and while the FMF 4.1 exhaust made the powerband broader and easier to use, it is only step one. (2) There is a learning curve associated with removing the clip on the muffler insert. If you are too aggressive in figuring it out, you may bend it.

If this was any other bike, we’d give this exhaust system four stars. It makes more power, effects the powerband across a wide range and adds dimension to the engine package, but you can’t make a silk purse out a sow’s ear. The FMF 4.1 exhauts does the best it can with what it has to work with.


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