Hmmm I just measured up the diameter of the pipe at the flare, 230mm, damn, so the flares are close to 35mm each, no problem, but the box is only 400mm high, on the outside, so 350mm inside, damn. Could I offset the ports, so make one stick 2" further out than the other? That way the flares will overlap, but it shouldn't be much air-flow restriction. I'll remeasure up the boot and see if I can wedge a slightly taller box in.
Also the ports should be 400mm long, or 435mm tip-to-tip?
EDIT: Hmmm I may end up having to sit the ports directly up against the top and the bottom of the box, so I will have to get rid of the inside flare (either sand it off or try to remould it to straight again), but only the section against the walls.So there will be say 300 degrees of flare on each port. Once on the outside the flares can overlap the 25mm for the roof and floor of the box. I'll have another go at measuring stuff up. But can the sub driver screw into the end joint? As in the sub mounting screws go in the baffle and into the side panel, or should I keep it in just the baffle?