Simply the cheapest way to Increase bottom end and midrange is with the Slater Skins High Flow Air Box Cover. Noticeable power improvement over the stock cover. Check compatibility listings for specific models and years.
YZ450F 2018-2022
YZ450FX 2019-2023
YZ250F 2019-2023
YZ250FX 2020-2024
WR450F 2019-2023
WR250F 2020-2024
Check our other eBay listing for the all New 2024 YZ 250/450F WRF 450 models.