Ported box specs for Alpine type r’s?

In the near future, my cousin will be building me two separate 12" ported boxes (slot port).  I am just wondering on the specs to give him to make the right size box in order for these type r's to sound good.  They will be going in the trunk of a 98 mustang so its going to be a tite fit.  I have heard to do 2 cubic feet and tune between 30-35hz.  Anyways im just trying to get the right specs on this because i know abs. nothing about box building so any help is appreciated.  Thanks.

One thing anybody here would need right off the bat is "what model type r" are you referring to?  Other than that, give a long look at the alpine site, go to tech center > consumer and find the tech sheet for the sub model you have or will be getting.  See if it recommends something.  And if you are, by chance, using two subs you should think seriously about having just one box built for the both of them.

I see what you're saying.  If you had them separate you could shuffle them into the trunk and then get them into position.  I was thinking that a single box will just flat out take up less room...less walls and less port area and port walls,  which add to the cubic feet.  And less weight.  Why don't you measure the opening into the trunk to try to find out how big the box can be so that it can be put in.

If you end up thinking that two boxes would fit in easier, then we'll work with that.  Did you look up anything on the website?

https://www.alpine-usa.com/support/main/support.htm  Click on Alpine Tech center on the left side, click on "continue without login".  I doesn't look like it's working right now...