They are 5 3/8". The guy that did these kick panels did a lot of back and forth with me in the car , so we found like the "sweet spot" where ny foot was NOT kicking the enclosure yet there was enough angle so the front stage could be lifted up at ear level.
Steve has seen and heard the system. If you want we can hook up and you can get a better idea about the whole layout, front stage, amp rack, sub enclosure and what not.