Box for 2 NVX VCW124's

[Chrisj10012]

I'm looking for help designing a box for 2 12's. ( https://nvx.com/vcw124-12-1000w-rms-car-subwoofer-dual-4-ohm/#other-details )

I've played around on subbox.pro but I'm not going to pretend that I know what I'm doing.

So I have enough space for up to 16 inches in height and depth and 40 inches in width.

I'm looking for a ported box tuned to 35hz. The manufacturer calls for 1.85 cubic feet for one, so I'm assuming 3.7 cubic feet for 2?

I currently have a RF P500X1bd ( https://www.rockfordfosgate.com/products/details/p500x1bd/ ) I know its giving me less than half ideal RMS for the 2 12's but if it doesn't give enough output I would upgrade to the P1000X1bd ( https://www.rockfordfosgate.com/products/details/p1000x1bd/ ) Still less than the 1700-2000 but I want the amps to match and I have a punch amp for the mids/highs.

https://subbox.pro/en/design/?bt=2&bw=1016&bh=406.4&bv=104.8&mt=19&fp=1&sq=2&ss=12&cd=286&md=177.8&sv=2&so=0&sd=25.4&sb=&sn=&pt=3&pq=1&rf=35&pd=203.53&pw=2&pa=325.18&pp=100

I'm not sure what I've put in correctly and what I've put in incorrectly but I know power is a factor, but not one I can apply to this.

If you need more information let me know. Any help is appreciated.