You have to be careful throwing around phrases like "stealth box" because there are a few different folks using the term now. I'm going on the assumption you're referring to the JL Audio StealthBox. (They probably have a trademark on the term anyway.)
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The stealthbox system designed for the convertible is exactly that -- designed for the convertible. You don't want it in a coup. The subs are shallow because our top takes up so much room in the trunk. You don't have that problem, so take advantage of the space you have.
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