I am buying MMA fight shorts, not board shorts. Im size 29 and they have...

[BGTONY]

...28 or 30. Which should I get? I have some compression pants with the cup slot that I will wear under neath. I'm thinking it will be more comfortable at 28.
They are split seam so know prob with kicking
Well on Sprawls site it says to go with the lower size
and I dont want them falling off

i have both sizes i have size 30 taken down they fit better with a cup than 28