I have six on my tower (see profile pic). I also have them inside the boat. They sound great in the boat but to be completely honest, hard to hear from 75' back while riding. Don't remember how many amps I have pushing them but I can look it up when I get home tonight. I have one amp just for them. I spent a decent amount of money (for me) on this set up but would do it differently next time. I explored Wetsounds which sounded awesome but really didn't like the way they looked installed (too big for my tower/boat set up). So, I went this way and will live with it for now. It's OK, just not great.