I have the Boom Stage 1 in my CVO RGU. 1 300 watt amp running 4 speakers. That's 75 watts each. I can hear mine fine all the way up to about 80+. Now I didn't say that it was as loud as I want it to be at times, but I can hear it fine.
So something is up with your system. Like Bless0 said, you should have 2 amps if you have the true Boom Stage 2 setup.
Now to answer your real question, assuming you have the true Boom Stage 2 Setup and it is setup correctly and you still want more, then your only option is to scrap the Boom POS and go aftermarket. Do some searching right here on this forum. There are lots of talk about it.
By the way, I will be scraping my Boom system asap for something better.