Getting ready to install the WS-420 in the V226, question about amp setup?

I'm pulling the boat out of storage on Thursday and hopefully taking it to the stereo shop on Saturday to get the WS-420 installed and tuned...but before I set up the appointment, I wanted to double-check to see if my amp setup is going to work well with the WS-420?

Currently I have:

1. 5-channel Arc Audio XDi 805 running my 6 in-boards and a 10" Arc Audio sub (has sub channel)
2. 4-chanel Arc Audio XDi 804 running my 4 Bullet tower speakers

Question:

Do I need to have a stand-alone sub in order to have the WS-420 perform correct? I haven't been challenged with power/need for MORE volume so if I don't have to mess with more amps, I don't want to! Otherwise, I can order the Arc Audio XDi 600.1 sub amp today and not have any issues!
Thanks!