Box help!!! For treo ssx 18

[Stevo55]

Ok guys new to the form. I have a good understanding of audio stuff. But this box is killing me. Iv build a few ported and 4th order and have been very happy with them. So long story short just got pristine treo ssx 18 that's was ran under powered and was in a show truck so not much use. Treo recomends 4.0 cu ft net 50sqin vent at 21.5 long witch gives it an f3 of 31hz I assume that means box is tuned to 31hz I can not for the life of me get all those specs to match exactly. Do I realy need to build it by their standards or no. I like it low and loud and have never used a company's exact specs I usually just build what fits in the vehicle nothing stupid like way to big or way to small and tune that box to 32hz is the port area and all that a huge factor or not. I have plenty of space to work with just one single 18 in an 06 durango. Was wanting sub up port back. Wanted a 4th order but have heard that's not best for suv. Any help would be much appreciated. Yes it will be very under powered for about a week before I get bigger amp thinking wolfram 3000.1 or skar 2000.1 at 1ohm or 2ohm what do y'all think 

[YukonXL04]

Being a 4" coil, rated for 2500 rms. I would think you would want atleast 3k-4k on tap since your trying to hit 150 with it.

 

4 cubes is really small for an 18. Might be good for power handling in comps, but I dont think it would be very versatile. However I have no experience with treo subs

[Stevo55]

That's what I thought I was thinking 6+ cubes at least but I mite be wrong.