A7 Port advice

[Elitopus1]

I would like to stiffen the flares on my 828 clone cabs. The problem is the motor board doesn't extend all the way to each side wall. Maybe I should either replace the motor board with the wider version or find some other way to seal off the flare area. I have heard about filling it with sand but worry about blowing out the flare

Also in response to GM's post about cab resonate frequency, have you worked with MDF 828 cabs? I have heard that their resonate frequency is much lower than plywood since they are less rigid. That is one of my reasons for extra bracing