WHAT IS IT? The FMF 4.1 RCT exhaust incorporates the latest FMF four-stroke technology in an array of materials and colors to fit your budget and style.
WHAT’S IT COST? $899.99 (full titanium with carbon fiber exhaust tip), $849.99 (full titanium), $674.98 (complete aluminum/stainless steel system).
CONTACT? www.fmfracing.com or (310) 631-4363.
WHAT STANDS OUT? Here’s a list of things that stand out with the FMF 4.1 RCT exhaust system for the 2016-18 Kawasaki KX450F.
(1) Installation. The FMF 4.1 complete exhaust comes with hardware that replaces both fasteners on the muffler. Do not use the stock hardware, as the front fastener is too short and the rear is too long. We used the OEM header nuts with the supplied pipe springs to mount the FMF head pipe. It is best to mount the head pipe first, but don’t tighten down the head-pipe nuts until the mid-pipe and muffler are lined up and their hardware is installed. Installation was a breeze.
(2) Stock trim. The 2016 KX450F’s engine was nothing like its previous powerhouse predecessor’s. The new engine ramps up slower and is very linear across the board. It is very easy to ride, but that’s just a nice way of saying that it could use a lot more power to run with the KTM 450SXF and Yamaha YZ450F. On the dyno, the 2016-18 engine actually performs better than the 2015 engine, but on the track it is a different story. The strong midrange we loved so much on the 2015 KX450F engine is gone for 2016-18. Every MXA test rider wanted more from the KX450F powerplant. That is where the FMF 4.1 exhaust comes in.
(3) FMF performance. The best way to describe the 2016-18 KX450F’s engine is “plugged up.” Something feels like it’s holding it back (pulling in the reins). The FMF exhaust system popped the cork on the 2016-18 KX450F powerplant. It felt like 2015 all over again. The strong midrange hit and pull to the top surpassed that of its predecessor. The only part of the curve that stayed the same was the over-rev. The difference between the OEM exhaust system and the FMF exhaust was night and day. If you’re unhappy with the lackluster power of your 2016-18 KX450F, the FMF pipe is priority one for turning this trail bike powerband into a true-to-life race engine.
(4) Weight. The stock header and muffler weigh 8.6 pounds. Our full-titanium FMF exhaust with a carbon fiber tip weighed 5.6 pounds.
(5) Options. The FMF exhaust system comes with a spark arrester insert that doubles as a sound regulator. The insert quiets the bike to a whispering 94 dB. Although we tested the full-titanium system that retails for $899.99, you’ll get the exact same power gains with FMF’s aluminum/stainless steel system for $200 less (and it still saves 1 pound over stock).
WHAT’S THE SQUAWK? No complaints.
MXA RATING: When the stock exhaust is replaced with an FMF exhaust system, it turns this dud into a stud. This is the one and only modification the 2016 Kawasaki KX450F powerplant needs right off the showroom floor.