I got sick of waiting and emailed them in hope of some news.
"Hey, huge fan here. I own 5 of your tanks.
I'm about to buy a 22 ci 4500 tank from amother brand for my pump setup, but I really would rather buy ninja. Any chance you guys are making thing in that size soon?"
"Thank you for choosing ninja and I am sorry to say we will not have that size for you to buy in quite a while."
I have not seen or heard of this yet so forgive me if its old news, but at the end of this video a guy from impact paintball talks about and shows a prototype tank from ninja. Its carbon fiber, 23 ci, 4500 psi, and meant to fit in stocks. He also "speculates about 15 ci and 10 ci versions.
If / when it comes out ima cut a tennis ball in half https://youtu.be/M0bNetDGTL0