I have two pairs of DBot5 speakers that I've been looking to sale since last year - http://dbot5.com/wakeboard-speakers/
. I have a 8" pair and a 6.5" pair, and I believe in the hardware kit, they come with a specific mounting bracket for Malibu towers (looks like a flat, thick piece of aluminum that slides into some kind of bracket).
Let me know if you might be interested in this setup. I was running it off a JL 300/2 amp and they sounded awesome.