Elevating subwoofer about two feet off the floor

I have my REL S5 on a Symposium platform which elevates it about 3"..It sounds much better than when on the carpeted floor..

Okay, coming back full circle to the beginning of the question: is it useful to elevate the sub? I bought a full round ASC tube trap that measures 20" diameter and 30" high. I placed the trap just to the right side of the right channel KEF LS50 monitor speaker and set an SVS 2000 sub on top. I think the result was phenomenal. Tight tuneful bass that was in the middle of the sound stage. You can see the tube trap here:  http://www.ebay.com/itm/371567367597?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Hmm tweak you must be in NYC since they were only doing local pick up.   I might have gone for these myself if I had seen them.   

Emailists,They have some for sale on another listing, but are higher priced.
http://www.ebay.com/itm/TUBE-TRAP-Room-Treatments-FOR-PICKUP-IN-NYC-/371636446080?hash=item568742238...

I know this thread is old but I just raised my subs about 2 feet off the floor.  I use small Pinacle subs that are dipolar.  My idea was to get the subs out of the mess that is floor level.  

Right away there was improvement. At first I thought they were louder but now I don't think so.  Now I think they're just more integrated and clearer.