Raising Subs?

Curious if anyone has raised their subs off the floor. If so, what was the result. Much difference?  I have 2 small subs that run at a very low volume level and am actually pleased with the setup. But if there would be a SIGNIFICANT improvement.

Also they are in a down firing configuration. Any improvement changing to front firing?

Like I said, I like what I have, so improvement would have to be very noticeable.

Thanks in advance.