Integration of a REL B3 subwoofer

I have a new B3 subwoofer that I am tinkering with. It's sounding better, but its hard to know whether there is more performance to be found somewhere. Some of the changes are so subtle that its easy to miss them. The manual says to put it in a corner, but so far, it seems to sound better out of a corner, halfway between the two main speakers. Anyway, does anybody have any war stories or tricks to share about things they did with a B3 (or any of the other B's) that seems to work well for optimum integration. Phase, crossover, gain, ect? Thanks.