Update:
Just had a long conversation with the EX-SPL maniac (splfanatic) relating to the design of the box for the subwoofer........ and it will finally be in the car in 2 days time 
Box Specs:
35"x17.5"x17.5"
4cuft net tuned to 34hz
3/4" malaysian Lasani , all screw's, resined corners from inside, 45* angled corners and double baffle, with the outer part of the box finished with potein and then paint, covered it with fabric to prevent major damage to paint