I talked to Branden, he wants $100 for the rear enclosures. If you want more airspace I'm sure Branden could modify the enclosures to your specifications.
Although I'm using 6 1/2's in back and they sound great.
The tweeter enclosures are $100 as well, which doesn't include the shipping of your side view mirror covers. He needs the covers and the brand name of the speakers you intend to use to make the tweeter housings.
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2000 Insight - Silver - 89,856 miles at 62.3 lmpg

- Tinted Windows - 6 Speaker System - MIMA Modification