ACS tube trap states that raising your sub off the floor results in better Bass reproduction. They further say that you should raise the sub off your floor 22% of your room hght for best results.
So silly me gave it a try. WOW! A substanial difference. I thought I had no lag, hangover or boom until I did this. It was like getting a better Sub. Amazing. Simply amazing.
Of course they sell a bass trap designed for this purpose, but you can make your own or just raise it up with no trap.
Say your clg. hght. is 8'-0", multiply that by 22% [ approx. 21" off floor ] and that is where the sub should be raised to. It may be ugly but it is very affective. Give it a try and report your findings..
rollo