2 x DLS Nordica 10i | Subwoofer Box Design

[mithatcann]

I have 2 x Dls Nordica 10i. I need to calculate to box of them. I would appreciate the help.
I read from the interhet that Peter Flodqvist was the man behind the Nordica 10 project when he worked at DLS. He recommended 19 liters also. I shared screenshot from dls nordica manual below.

What is your advice for 2 x dls nordica 10i's subwoofer box?..

[chithead]

[mithatcann]

19 liters yes.. What design would you suggest for the 2 products?