I am thinking of building a box for my 2 12" Type R Subs. Currently have a Bassworx box. The size I am thinking of is External dimensions of 40"x16"x18". I will be using 3/4" MDF but doubling it up, so 1.5" width. The Internal dimensions per chamber will be 17.75"x13"x15" with a port that is 1.75"x13"x23.3" that is tuned to 33hz. I will be using 3/4" for separating the chamber and the port. Just curious if that sounds good for a box. Will be putting it in a 04 Sentra.