FMF Dual Titanium Factory 4.1 RCT Muffler System

Keefer Inc. Product Evaluation 

FMF Dual Titanium Factory 4.1 RCT Muffler System

The 2017 Honda CRF 450R has an incredible engine package stock. The snappy throttle response and free feeling of the motor makes this one of the most fun engine characters in the 450 class. This doesn't mean it can’t get better however. FMF wasn't the first to the game when the new generation Honda CRF 450R was released. In fact, FMF waited longer than it would of liked to release their 4.1 dual muffler system, but they wanted to ensure it wasn't just good on the dyno, but good on the track as well. I took delivery of FMF’s Dual Titanium 4.1 RCT muffler system and installed it in less than 10 minutes (which is a great time for me) and was able to head out onto the track. There were no joints that binded or misalignments when assembling the FMF system 

I have ridden with Yoshimura and stock systems on the 2017 CRF450R the most recently. I have a good feeling of both of these systems, so breaking down the FMF system was fairly easy to dissect on the track. The FMF 4.1 muffler system has incredible amounts of bottom end and throttle response. The bottom end comes on strong and the Honda keeps its exciting, crispRPM response feeling, but lets you run third gear through corners a little more than the stock or Yoshimura muffler systems can. Downshifting to second almost makes the Honda a little too much too handle with the FMF system installed (on roll on) through some corners. When going to the FMF 4.1 system I reverted back to map 1 (standard map) instead of map 3 (aggressive map). Since the FMF has so much bottom end I could use the standard map instead of having to use map 3 like I do on other systems. Mid range is broader and pulls farther than the stock muffler, so using third gear is almost the perfect gear for most tracks (with stock gearing). Through mid to top end the FMF system almost mimics the Yosh in pulling power feeling on the track. Over-rev isn't increased dramatically over stock, but I did notice that you didn't need to rev the Honda with system as shifting early was a welcomed attribute to the American made muffler. I did notice that the FMF system is louder than the Yoshimura and stock systems, but keeps a race oriented deeper sound. 


It takes you a little while to get accustomed to the sound once on the track, but the good news is that the muffler packing has lasted past the 12 hour mark and hasn't changed much to the ear. I used to get only 8-10 hours on other FMF muffler systems, but the dual Honda system has proved to be more durable. the system is light at 8.3 pounds and will remove a couple pounds off of your stock system. 

In my opinion this is one of the best mufflers that I have tried for the 2017 Honda CRF450R. Yes, it is louder sounding than others, but the increase in power feeling on the track makes it hard to beat. If you're looking for an exciting feeling muffler system that performs as good as it looks the FMF Titanium Factory 4.1 RCT Muffler System is a good buy. At $1299.99 it is slightly less money than its competitors and for as long as we all waited for Don and the fellas at FMF to get it out there, it is well worth the wait. You can go to to order yours. 

Have any questions about this test? Feel free to hit me up at and I will do my best to answer any reasonable questions for you.