WHAT IS IT? The Factory 4.1 exhaust with MegaBomb head pipe is FMF’s premium exhaust system for the 2014–2015 Husqvarna FC250.

WHAT’S IT COST? $899.99 (titanium/carbon fiber end cap), $849.99 (titanium/titanium end cap), $699.99 (stainless/aluminum).

CONTACT? www.fmfracing.comor (310) 631-4363.

WHAT STANDS OUT? Here’s a list of things that stand out with FMF’s Husqvarna FC250 Factory 4.1 exhaust.

(1) Models. FMF makes three versions of the Factory 4.1 for the 2014–2015 Husqvarna FC250. MXA tested the RCT, titanium, anodized, full system with the carbon fiber end cap. It is made from titanium, the canister is anodized blue, the end cap is carbon fiber, and the head pipe offers MegaBomb’s Resonance Chamber Technology (RCT). For $50 less, you can order the Factory 4.1 with a Ti end cap and the option of anodized blue or natural Ti canisters. If you don’t mind the extra weight, FMF also makes a stainless steel header with aluminum muffler for $699.99.

(2) RCT. FMF’s Resonance Chamber Technology (RCT) consists of the MegaBomb resonance chamber in the head pipe mated to a specially shaped muffler core. Resonance chambers not only help lower sound levels by approximately 1 dB, they also allow for a shorter overall tuned length of the system, which means greater centralization of mass and a reduced risk of crash damage.

(3) Performance. In stock trim, Husqvarna’s FC250 has a powerband that starts off mellow and then steadily ramps up until it revs to the moon. The FC250’s powerband is unlike all the other 250 four-stroke powerbands. It offers class-leading horsepower, but it is the most difficult power to use. It is linear, slow-revving and doesn’t make max power until the very top. When we bolted on the FMF Factory 4.1 system, our testers were grinning from ear to ear. It improved the powerband from the bottom to the top. Test riders were able to use the clutch less thanks to new-found power in the midrange. It kept on gaining power on top and did not lose an ounce of over-rev when the engine was wound out. Every one of our testers loved FMF’s FC250 exhaust. We were surprised by the power gains throughout the entire powerband.

(4) Fit. The three-piece FMF Factory 4.1 system slipped right in place. The fit was tight, but thanks to FMF’s separate mid-pipe, there were no issues.

(5) Sound. With increased packing volume in the irregular-pentagon-shaped canister, plus quiet inserts and a removable spark-arrestor screen, the FMF Factory 4.1 can pass all the current sound tests. The MXA wrecking crew, however, preferred to run the FMF system without the quiet insert to make the most gains.

WHAT’S THE SQUAWK? The RCT chamber bulged out enough to melt the test rider’s boots.

Either this is a great pipe or a bike in desperate need of help. We think it’s a little of both. We’d run it in an instant.