ekkk. 1600w boss amps.. a friend got that a couple months back, i warned him but "nah nah its 1600w bro. a friend is giving me a good deal too!". 1 week later, his amp was F'd.

anyway u should be able to fit 6-6.5 easily. speaker depth is more of a issue.

tweeters.. a-pillar, that triangle thing, in the kicks, in this.. empty spot on ur doorskin right below that triangle thing and next to your door handle.

battery.. hook it up 1st & if theres no electrical issues (dimming lights, voltage drops) then you should be fine. id upgrade the wiring before getting a new battery anyway.