Subwoofer for Wilson Maxx2

my room is about 22x33 ft, my maxx2 are sitting about 11ft from the front wall, and 8,5 ft apart

i get very good image, width..depth..etc.., however not enough bass

i tried to locate the maxx closer to the front wall, from 4 ft..etc.., however at 11ft everything are better, but not enough bass

so i want to add 2 subwoofer ...wondering any Maxx2 users or full range speakers user are running subwoofer and able to give me some suggestion ?

i do not want to spend that much for Wilson Sub...