I'm considering a timber tractrix horn with a GPA 399. It will have an Fc of 250Hz & the mouth dimensions will be 23" wide X 9" high x 16.87" deep with a 1" motorboard. It will be similar to the attached pic.

There's plenty of info to determine the lowest frequency that the proposed size horn will go to, the program used to generate the dimensions will calculate this & many other things. My problem is determining how high this horn will go to.

Would anyone know if it will go up to the upper limit of the driver? That is, to 15K?
Thanks,
John