Exhaust question 300GP/18 and EC300/19

[Doc Brown]

I drove my buds 2018 300 GP model and my EC 300 2019 back to back. While the power isn't much different I felt the GP revs further while mine runs into "the natural rev limiter" earlier.

I think its the pipe. My KTM loved the FMF Fatty. Unfortunately on the GP's pipe it says just "FMF" but I have no clue which one it is.

Any ideas?

ta
Doc