People w/ subs in rear door...

[Navigator]

...The rear hatch was made to hold the weight of a heavy spare tire, so by comparison a sub is no big deal. No problems detected after 2 years of use, so I'd say it's safe and has no negative effects on anything.

You'll have to come to a local meet to find out how it sounds, I can tell you mine is awsome, but you've got to hear it for yourself Mine is a custom sealed unit inspired by Tone's baffle board.