Hi, I have a Fi BL 18" that I traded a friend for. He ordered the sub new with daily option and flatwind coils he told me. It is currently in a 5.8 cubic foot box tuned at 33hz. I have some music that gets pretty low and when the notes drop low the sub bottoms out pretty easy. The subsonic filter is on right around where the box is tuned at. I even turned it up a hair more. I have seen other Fi's move almost like they cant bottom out like the ssd and btl. Is the BL's xmax just really small for Fi or could I do something to help. I am going to build a new box that is 6 cubes tuned at 28.8hz. I was also going to get an audiopipe 1500 but im not sure since it is bottoming out this easy on the audiopipe 10001D. Any suggestions would help.