Removable ports?

[BulldogSr04]

how would you design something like this. like a removable port to tune higher for competing. how is it held in place? anybody have any insight on this? i am thinking of doing this for an spl box for a daily driver

[SPLNOMA]

i have done this in my bos 48 for comps and a template that drops in and tunes it to 28 for dailyhttp://www.sounddomain.com/id/sqlnoma