i don't know if this is what you're looking for, but i use MDA's subsynth, via a send from my kick, to provide a 50hz "boom". there are a few different settings for 'type'. i use 'key osc.' and then monkey with the others to get a dense, solid "thud".
There's a sample called like "Euro Dance Kick" or something that sounds absolutely MONSTROUS, look for that one. It's worked out for me better than any of the normal 808 samples.