In my experience, John is right on the money.
I too live in a home with cement floors, and was amazed one day to help set up a friends sub in a home with wood flooring. The tactile sensation you get in such a room is completely missing in my room.
But, I took some advice from the docs that came with my HSU 1225...try near field placement. Holy crap! What a difference. Right now I have the 1225 laying behind my couch, between the couch and the back wall. There are times during certain films (Sky Captain, SW AOTC) where you would swear that the couch is lifting off of the ground.
My family is usually very unimpressed with anything I have done in my rig, but they were amazed at how things were transformed when I moved the sub. If your room will allow you to do so, try placing it close to your seating position.
Brian