port tuning frequencies

I think I may be confused here.  Will A lower tuned port bring the low deep bass compared to a higher tuned port?  I read somewhere for spl you tune higher. I am putting a 15'L7  into a 6.525ft^ gross enclosure, powerd by a zx750(big3 upgrade) I want the low deep bass you can feel. Do I wanna tune the port to 30hz or lower? I don't plan on trying to compete or anything I just want to feel the bass.

         I_also_want_the_boom

There isn't any one generalization on tuning.  Some subs, because of the limitations of enclosure size inherent in car audio design, demonstrate a substantial peak in the higher SPL freq range...even without the added help of a tuned port.  Those are often recommended to be tuned lower so that the audio freq spectrum may be evened out somewhat so they aren't just one-note wonders.  Other subs demonstrate a more even reponse across the spectrum and then therefore can be tuned to a frequency that interplays loudest with the vehicle.

Other ways of tuning involve tuning ultra low so that the port sound interferes the least with the sound from the sub enclosure.  This may be a case where the sub requires a port but the goal is SQ.  But in every case, every sub behaves differently from the others.

A woofer's life won't be shortened by box tuning method, in itself.  But when tuning higher to the SPL range, establish the lowest freqs that the sub can handle in that enclosure and set a subsonic filter on the amp to protect the sub from becoming unstable.  If the setup is accurate and filters and gains are set correctly for the gear, the woofer will last its expected lifetime regardless of box tuning frequency.