This is a subject that I've been interested in for quite a while. Actually bought a set of the Hog Tunes woofers for lowers, but haven't installed them yet.
The bottom line in the debate regarding sound on motorcycles is this: No matter how much you spend, you'll never get decent sound on an open vehicle going 70 mph. The best you can hope for is to be able to hear words and guitar solos. Even then, the volume has to be up high enough to deafen you after several hours on the road. Notes in the bass clef will never be clear at tolerable volumes. By tolerable, I mean at least 130 decibels. Seriously.
I installed new 7" HAT (from Biketronics) speakers in the fairing and the passenger pods, with their 180 watt x4 channel amp, and I can hear vocals and solos marginally better than stock while riding. They sound good sitting in the garage, tho. I still cling to the hope that something will allow me to hear ANY bass while riding, but I'm beginning to accept the limits of physics. That's why I might try the Hog Tunes, but I really like the convenience of a little storage in the front lowers.