I am trying to plan how I am going to build a box to go in the ex cab of my toyota truck. I am putting 2 Fi Q15's in it. The space I have to work with is 53'' wide 17'' depth and 22'' tall. I was told to use 1 layer of 3/4'' MDF then after the box is done add a 2nd layer of 3/4'' MDF to the outside of the box to help reinforce it, is this right? This is the first box I have build so I just wanna make sure I get it right. But this is what I have come up with so far, how does is this right, the subs call for about 4 cub feet each tuned to around 33.

I am trying to plan how I am going to build a box to go in the ex cab of my toyota truck. I am putting 2 Fi Q15's in it. The space I have to work with is 53'' wide 17'' depth and 22'' tall. I was told to use 1 layer of 3/4'' MDF then after the box is done add a 2nd layer of 3/4'' MDF to the outside of the box to help reinforce it, is this right? This is the first box I have build so I just wanna make sure I get it right. But this is what I have come up with so far, how does is this right, the subs call for about 4 cub feet each tuned to around 33.

The only spot you really have to add a second layer of mdf would be the front baffle (where the speakers go). I ran the numbers for you. The area you have to work with is 11.47cuft. After wood displacement you are at 8.88cuft with a split chamber. After your port displacement and sub displacement you end up with a 5.9cuft box. So each sub would be in a 2.95cuft box. Which works cause fi recommends between 2.8-4cuft per sub. Now if you get fancy and do bracing and 45 degree corners you will go below what fi recommends and in return choke the subs.