The height adjustment is easy...
Since these will be cast the diameter change may be a little more difficult.
I can change the model and see what happens in the casting. I've thought about ditching the divided housing and merging the two inlets in the pedestal to make more room.
What diameter up-pipe would you like to see?
As far as ordering... that may be a while.. I'm just getting back on these. I can however provide the laser cut flanges and you can DIY creating your own tubing inside. The uppipes could then be lasered to whatever size you want.
Brayden