If you are building Studio two π speakers, just make sure that your port length is 1.875" (1 7/8") from entrace to exit. The front of the speaker face to the edge of the port inside should be 1.875". So if the baffle thickness is 0.5", then the duct material should extend 1.375" (1 3/8") into the cabinet interior.

Be sure to brace the cabinet very well, so that it is solid when you rap on it with your knuckles. You want it to sound like a rock, not a drum or a keg. You're probably alright on Studio two π speakers but the towers will definitely need braces. There are lots of good suggestions here in this forum, so you might do a search for "brace."