WHAT IS IT? FMF makes both single and dual exhaust systems for the 2019 Honda CRF450. In the past, we have preferred the single exhaust because of its superior performance. But, we felt we were doing a disservice to CRF450 owners by not testing the FMF Factory 4.1 RCT dual system.

WHAT’S IT COST? $1,499.99.

CONTACT? or (310) 631-4363.

WHAT STANDS OUT? Here’s a list of things that stand out with the FMF 4.1 RCT dual exhaust for the 2019 CRF450.

(1) Installation. To remove the stock 2019 CRF450 exhaust, you will need 8mm, 10mm and 12mm T-handles or sockets. During this process, be careful not to damage the gasket inside the muffler that connects to the head pipe when wiggling the mufflers off. When installing the new FMF head pipe, be sure to leave the 12mm nuts loose to allow for some free-play, which will help align the new system. Be careful not to lose FMF’s clip nuts, and don’t tighten anything down until both mufflers are in place. 

(2) Weight. The FMF CRF450 dual exhaust is 100 percent made in the USA. The pipe is constructed from titanium with blue anodizing and a carbon fiber end cap. It weighs 8.6 pounds. The stock CRF450 exhaust weighs 10.8 pounds. 

(3) Stock trim. The stock 2019 Honda CRF450 has the most aggressive power in its class. A lot of MXA test riders struggled with the explosive, jerky hit out of the turns. Make no mistake about it, the CRF450 is fast, powerful and, at times, a handful. Additionally, there was a sluggish section in the powerband between 5000 rpm and 6500 rpm. Max power with the stock exhaust is an impressive 60.25 horsepower. 

(4) Performance. With the FMF 4.1 system, the MXA test riders enjoyed an enhanced spread of power off the bottom. It filled in the flat spot, which in turn lessened the aggressive hit. The boosted midrange—from 5000 to 6500 rpm—allowed test riders to ride in a higher gear through the turns. The peak horsepower was only slightly higher than on the stock pipe (60.55), but peak power is not as important as the breadth of power, and the FMF pipe filled in the bottom and was much stronger on top. The stock pipe fell off dramatically after peak, while the FMF pipe kept pulling for almost 1000 rpm more.

WHAT’S THE SQUAWK? Price. The $1499.99 price tag is a byproduct of doubling the material and labor costs for two mid-pipes and two mufflers. For comparison, the FMF 4.1 RCT Ti single exhaust costs $874.99.  

MXA RATING: The FMF 4.1 RCT dual exhaust system adds power from the lowest rpm to the highest. Best of all, it controls the hard-hitting nature of the CRF450 engine. It makes it more manageable, which is better than more powerful.


2019 honda crf450exhaustfmffmf 4.1 rct dual exhausthonda crf450motocrossmotocross exhautsmx pipesmxamxa team testedtitanium