hey guys i have a box in my 2000 grand cherokee in which i had a single sa15 but now the sa15 is sold and i just bought a Zv2 15.. my box is 36.5w 14.5h 11.5d and the slot port is 3x12x19 so i know i need to make the port bigger im just not sure how big it has to be.. trying to tune it to 32 htz... any input would be wonderful thanks