Expanding on the narrow baffle: In a FAST there are 2 numbers to look at when picking the XO.
If you are using "turning up the woofer” to accomplish bafflestep compensation then the XO should be in the range of 0.707 to 1 times the BS(F3).
Ideally the XO frequency should be such that the C-C of the XOed drivers correponds to less than the ¼ wavelength defined by that C-C.
The 1st gives a range (410-580 Hz), the 2nd a maximum XO frequency (480 Hz).
I note that he is putting a 5° tilt on the baffle, something we 1st did with Tysen, and he has missed a few other places where a design tweak could subtly enhance things.
dave