First impressions of the FMF 4.1 slip on muffler on a new 2022.5 KTM 250 Factory Edition: back to back with a stock 2022.5 KTM 250 Factory Edition. The FMF was shipped without the insert installed so we rode it that way. It is definitely louder than the stock muffler. With the FMF 4.1 slip on the low to mid throttle response is similar to the stock muffler but the highe RPM's (upper mid to top end) the engine feels a bit freerer revving. I was hoping for a bigger difference but it seems the stock KTM muffler flows well and is a good balance of power and noise. I will ride the 250FE again with the FMF spark arrester muffler insert installed and see how that effects the power feel. We will also try the full FMF exhaust once the FMF Powerbomb header is available.