Check out www.cyclesounds.com. I had their 3" system on my Vstar and loved it. The sound was clear, loud as you want it, and not intrusive on the handle bars. They have various systems. I had great service from them, and had no issues with the system after install.
The prices are high, but you get what you pay for. They also have some good alarm/immobilizer ideas.
No affiliation, just a happy customer.