Replacing rear 8" speakers in S70

[Auburn T5]

Hey guys I've discovered that the rear deck speakers in my S70 are 8" woofers with a small tweeter across teh top.

I've got a pair of 8" MTX subs, a good amp and wiring not in use and I'm wondering if I line the top and bottom of the deck's sheet metal with the peel and seal or b-quiet liner, would the subs sound decent?

I'm not looking for huge quantities of bass.. just a good amoutn to fill in the compltetely lacking low end right now.

I know they're open air so I'm curious if a supplimental box would have to eb somehow fabricated belwo teh speakers in the trunk on the underside of the rear deck or if they'd sound fine open air?

Also, would any modifications be needed to get them to fit or are they pretty much just drop in and plug em in?