I have a FMF Factory Fatty pipe for all 2017 KTM 250 / 300 bikes.
This is the KTM hardparts version, so made by FMF but with the KTM tag.
I have used the pipe for a total of 3.5hrs, it has two small rock dings that are reflected in the price. You are looking at close to $300 with taxes for a new unit.