I could be wrong but the rear of the box already has three 3" ports, can"t remember the length but when i did the numbers it worked out to 30hz with just over 6.2 cubes. i will 2x check the numbers and port length and let you know how I came to it. Perhapse I missed something that u may catch...

3 3inch ports is as good as sealed @ 6 cube

Been debating runnin sealed as well cuz would surely fit with room to spare and still get loud as hell. Not tryin to win any comps, just love my music loud but everyone keeps saying dont run sealed for some reason and i doubt that they have even tried them that way. With enough power they should do well sealed for a daily set up and only benefit more in the SQ department. Currently running a '05 RE XXX15 in 2.5 sealed after bracing and all displacements and sounds friggin AWSOME!! I cant imagine why 2 15's sealed would not be louder and sound even better. Is ther anyone who has run them sealed at around 2.5-3 cubes?? Please feel free to post your findings or opinions on sound and output if u have...

You can always run sealed for now and ported later . You can build that box you described you can build @ 6.8 cf and just add two 6 inch ports at 15" long if you feel it needs it. That will give you 35hz tuning and 2.9cf each . Forward subs and port . I would put the ports in the middle between subs

You know what?? I am gonna try it out sealed gosh darn it!!! I will put one of the SA's in a 2.5 box that i have to give me an idea of what a pair of them will sound like sealed. I will post my results after testing it out for a day or so on some different types of music. Im no pro but have a good ear and am prtty discerning when it comes to the sound of music. If it sounds anything like the sub im runnin now, i will probably seal the pair... If not, its back to the damn drawing board for ported!!

Alright.... for those interested, I swapped subs from the sealed enclosure and threw in the SA 15. Have not really adjusted gains on the amp or headunit due to lack of time. was doing it during work hours at my warehouse and got busy at the last minute. Anyhow, initial thoughts were: played well with all kinds of music and very tight sounding. Output was comparable to the XXX but not with the same authority if that makes any sense. Played very well on the low 30's to 70hz range but lacked the low end that i CRAVE below 29-28hz. That being said, the short comings ive described could have alot to do with not being tuned from the head unit or amp properly and the fact that i comparing it to a sub that carries more than twice its size in motor structure. I had a pair of SA12's last year with similar issues and once i went ported, it was AWSOME!!!!!! I expect nothing less from the 15's once I PROPERLY figure out how the hell to fit this monstrousity in my damn trunk!

Also forgot to mention that the Sundown SA15 is brand spanking new and suspension is ultra stiff. Perhapse a proper break in period may be in order to see how well these do sealed??

My ported 12 on 1500w was about as loud as my sealed 18s on 2500w. Go ported. I went sealed. Its nice but needs more authority. Kills the lows though.

Yup definetely going ported!! box build will start in about a week... some loose ends to tend to first.