Found these front and rear sway bars from Cusco x G-Tech for the 2nd gen NX. AFAIK these are the only performance sway bars that exist for this generation of NX.

https://item.rakuten.co.jp/autostyle/abaz000003/
https://item.rakuten.co.jp/autostyle/abaz000004/

A bit too much for me but maybe someone with deep pockets might be interested.