What box did you use?
This thread's pretty old, and none of these guys post here anymore.
Just take a measurement for height inside your trunk and then head on down to Best Buy or any other place that sells this stuff and get set up. The place I bought my box from actually let me stick it in the trunk first to make sure it fit before I bought it - my car's a convertible though so it's a little tougher to find something that fits right; hardtops won't have that problem. You may need to lay the rear seats down and stick it in that way, as the trunk opening isn't all that large.