The Octane ZR woofers are no more. They have a new line out called RSD. They are very close to the ZR series subs. As far as amps are concerned, make sure you go with efficient amps. Rocfords are not very efficient. Alpine PDX amps are. Class D amps are efficient for subs but can abuse them being that they work pretty much on a square wave. To make the woofer work better for the boat environment a vented or bandpass works well. The bandpass is self loading and will offer good output playing into an open environment as well as more efficiency. The drawback is you can't hear the amp clipping which can destroy woofers so a good shop is needed for building this enclosure and seting up the system. As far as mids and highs use 6x9 speakers as much as you can. I have used both together in boat systems and the 6x9 speakers are always more noticable while playing. Like the other people here have said. Stick with a good brand and you will be ok.