3x8 stack size?

[3 brothers]

got a leader 3x8 4'front 4' rear drop flue going to mount a blower to it also, what size stack should i be running? i'm thinking 12" any feed back would be great.thank you

[maple flats]

My 3x8 has 12" and it works very well. I have AOF blower as well as high pressure under fire blower (all on same blower)

[PARKER MAPLE]

My 3x8 raised flu has a 14in. It also works very well