For sale is a used 300 cylinder/ head kit for the 2stroke 2023+ ktm sx 250/300's. This kit was used to upsize my 2024 KTM SX250 to a 300. It has roughly 15hrs on it. Never had any issues. The used piston comes with it as well and new extra gaskets. You will need to get your ECU reprogrammed for a 300 if you are upsizing.