3 kicker comp vr 12s ported

what vehicle?? What amp?? How much space do you have?? What kind of output are you wanting??? smooth flat response or basshead bumpin??

Kicker's website will tell you all the specs for ports and cf for their cvr's.Perfection is the only standard.

how do i know what hz to set my ports to when building a box for my subs??

If it were mine I'd probably tune to 29 Hz, but if you want SPL tune it to 40 Hz.  You have to have a subsonic filter set at 20 Hz to prevent overexcursion.  Two slotted ports each 6" X 4" (or equivalent square inch openings of 24 sq in each) for a total of 48 sq in.  Each port length is 11.3".   This is figuring with a net volume of 5.25 cu ft airspace (port volume is additional).Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

No, what I posted is for what I said you should build for SPL:   Fb 40 Hz,  because you said you were aiming for SPL in your earlier post.  If you're competing you will have to have a lot of hands-on with this setup and work with it; probably work out a few different box arrangements and do extensive testing.  Do you know anybody who competes?  I don't do quick box workups on this forum with the idea that the user is going to win a championship with the box.  That can't be done by internet postings.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.