rear box flange 2.5"

I need a flange to suit my 5zigen miracle fireball rear box, pretty sure it's 2.5" pipe so it can match up again with my matching b-pipe.

Where can I get one?

Basically I took the original flange off the fireball to graft it onto an oem ek9 rear box for track days.

Now the fireball box has no flange.

Anyone? @Tegiwa Imports