Is there a conversion plate or something to allow someone (namely me) to install a 6x9 in a 5" space. I neglected to check out what speakers i had in the back and when i went to install those i found they were 5" rounds. My new speakers were in my trunk so long that the box got beat to crap by the sub, but the speakers are still perfect. Would best buy still take those back, or should i plan on giving them to my mom as a late birthday present?