Go to Offshores site and look up bl Feigao in the 540xl section. I see no lipos there. Lets see, i would go saddle packs and reason is big packs are loooong and hard to fit, so saddle packs make sense. 14.8 for voltage but i'd make a harness for series 7.4 + 7.4 =14.8 and i'd make a harness for parallel so you can double the mah's. Contact Steve at offshores and Steve will send you to
www.battlepacks.com but for me i go to Common Sense RC. I'm trying to be exact but it's real hard. One other site is Rumrunnerracing forum, there are just a few guys with the answers. My boats are 30" or less and i have 11 monos and 1 airboat.