Wanting to get the most out of my PA mids

I've got 4 unlawful sounds 8s and 4 unlawful sounds bullet tweeters im putting in my mazda 3, with the plan to buy 4 more of each. Currently have 1 machete 80.4 and will be buying another for the next 8 drivers. What should I do to get the most volume possible out of these speakers? currently have one set in the rear infinite baffle mounted on my subwoofer enclosure and they are doing good but I feel as though they could be doing better. Unlawful said I could do a 0.5 cube box each sealed, would that increase output over IB with these type of drivers? Also my door panels are incredibly flimsy. what can I do to not only reinforce the panel, but still keep it light weight and easily able to remove the panel for repair work. 

Plan is 2 amps, 2 tweets and 2 8s per front door, a tweet and mid in each rear door, and 2 tweets and mids in the rear mounted on/near the subwoofer enclosure.