[Chrisbee]

Right angled joints, or elbows, (and some other angles 15, 30 & 45 degrees) are all readily available for 4, 6 and 8" PVC drainage pipes.

Joints come in solvent glued and rubber sealed types. The solvent glued type have to be pushed home quickly or they stick partially out of the joint. Once the joint is made they stay together.

The rubber sealed joints will need a suitable lubricant if you ever want to take them apart again! The removal friction is enormous if you don't use a proper lubricant. Pipe wall brackets can be used to anchor your plumbing out of sight inside the box.

My understanding of reflex ports is that only the physical volume of the materials (the PVC itself) is calculated when discussing effective volumes of ported enclosures. Not the swept volume of the entire pipe.

I'd value a more knowledgable confirmation of which volume is correct.

I also understand that the effective port length is calculated by the center length of a folded pipe. Rather than the longest internal edge or the shortest internal edge of a folded pipe.