BOLD MAGENTA part numbers are new for 2026 EXHAUST PARTS-UNLIMITED.COM OFFROAD | 2026 EXHAUST 11 DISCLAIMER: *EMIS (EMISSIONS CATEGORIZATION CODE). SEE PAGES 4-6 FOR CATEGORY CODES, IMPORTANT EPA/CARB EMISSION DEFINITIONS AND REGULATORY COMPLIANCE AND NOTICE REGARDING NOISE REGULATIONS. PRODUCTS NOT LEGAL FOR SALE OR USE IN CALIFORNIA ON ANY POLLUTION CONTROLLED MOTOR VEHICLES IF NOT CATEGORIZED AS “1” OR “4”. QUIET CORE INSERT FOR FACTORY 4.1 RCT •Sold each NOTE: Fits late 21 and 22 mufflers. FACTORY 4.1 SLIP-ON MUFFLERS •Factory 4.1 muffler available in natural titanium or blue anodized titanium with titanium end caps •The lightest mufflers available •Superior power and performance – horsepower improved throughout the rpm range •Feature exclusive proprietary Chamber Core technology • Factory Forward Engineering centralizes mass, improves handling •Made from premium quality American materials •Customize with performance tuning inserts and spark arrestor module •Meet AMA sound requirements on most models; inserts available for others DESCRIPTION PART # Quiet core insert 1861-1666 FITS MODEL DESCRIPTION PART # EMIS* HONDA CRF110F 19-26 Slip-on muffler w/ stainless steel mid-pipe 1821-2018 3 Anodized titanium slip-on muffler 1821-2019 3 CRF125F 19-26 Slip-on muffler w/ stainless steel mid-pipe 1821-2020 3 Anodized titanium slip-on muffler 1821-2021 3 CRF150R 07-26 Anodized titanium slip-on muffler 1821-0547 3 KAWASAKI KLX140L/G 08-25 Slip-on muffler w/ stainless steel mid-pipe 1821-2022 3 Anodized titanium slip-on muffler 1821-2023 3 FITS MODEL DESCRIPTION PART # EMIS* YAMAHA WR250F 07-13 Anodized slip-on muffler w/ stainless steel mid-pipe 1821-0584 3 YZ250F 06-09 Anodized slip-on muffler w/ stainless steel mid-pipe 1821-0584 3 WR450F 07-11 Anodized slip-on muffler w/ stainless steel mid-pipe 1821-0584 3 YZ450F 06-09 Anodized slip-on muffler w/ stainless steel mid-pipe 1821-0584 3 FITS MODEL DESCRIPTION PART # EMIS* KTM 250/350/450 EXC-F/ XCF-W 08-14, SMR 07-10, SX-F/XC-F 07-15 Stainless steel slip-on muffler w/ carbon fiber end cap 1821-1633 3 Blue anodized titanium muffler w/ carbon fiber end cap 1821-1631 3 250/350/450 SX-F/ XC-F 16-18, 250/450 SX-F FE 15 Blue anodized titanium muffler w/ carbon fiber end cap 1821-1698 3 250/450 SX-F FE 15 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1719 3 250 SX-F 19-22 Blue anodized titanium muffler w/ carbon fiber end cap 1821-1925 3 350 SX-F 20, 450 SX-F 18-22 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1920 3 Blue anodized titanium muffler w/ carbon fiber end cap 1821-1921 3 350/450/500 XCF-W 20-23 Blue anodized titanium muffler w/ carbon fiber end cap 1821-2001 3 SUZUKI RM-Z250 19-25 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1958 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-1959 3 RM-Z450 18-24 Stainless steel slip-on muffler w/ carbon fiber end cap 1821-1857 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-1858 3 FITS MODEL DESCRIPTION PART # EMIS* TRIUMPH TF 250-X 24-25 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-2159 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-2160 3 YAMAHA YZ250F 14-18 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-16101 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-1612 3 YZ250F 19-24 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1883 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-1885 3 YZ250FX 20-23 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1883 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-1885 3 WR450F 20 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-2012 3 Blue anodized titanium slip-on muffler w/ carbon fiber end cap 1821-2013 3 YZ450F 18-24, YZ450FX 19-24 Stainless steel/aluminum slip-on muffler w/ carbon fiber end cap 1821-1838 3 Titanium slip-on muffler w/ carbon fiber end cap 1821-1840 3 1 QuietCore not included. FACTORY 4.1 RCT (CONT) 1821-2018
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