The problem was speed. Aura had to engineer a very large, very slow (Yet torquey as FUCK) boxer engine for their system to work. They couldn't get the RPMS out of it to make it a real application. As with anything, tech has improved, and now someone can.
Aura is now (It's not on their site, but I was invited to an investor symposium about 4 years ago) working on "Something else" that I'm bound not to talk about. But needless to say, the Bass Shaker was actually a side-effect of this invention.