[Trendy McFly]

In a 20'x15' small room I plan to wall mount a TV. I put speaker enclosures/ fire rated boxes in. One mounted horizontally above the TV mount, and two beside the TV mounted vertically. The fire rated enclosures have the following internal dimensions: 7" 11/16 width, 14" 5/16 height. They fit perfectly SpeakerCraft AIM LCR 5" series, or POLK 255C-RT speakers. I have had some second thoughts, and want to go super cheap and fit in some smaller POLK RC 65I speakers. I have the bare drywall in already, cut out around the enclosures, but not finished, textured, or painted. The enclosures have a lip around the space to install the speakers that protrudes into the drywall about 3/8", but does not stand proud of it.

Now, what do you think I should do to make the enclosures around 11" tall, subtracting from the already 14" 5/16 height they are?

I was thinking my options are:

Fein out the drywall from stud to stud below the box, say 6" down. Then Fein off the lip of the enclosure. Then replace the hole with a 9.5" piece of drywall giving me my wanted 11".

Stick a 2X4 piece of scrap in the box, screw it down somewhere, then put a piece of fascia drywall on it, and use excessive joint tape to make things smoothish.

weld? i think the boxes are steel

or lastly spend 200 ea on Polk 255C-RT or SpeakerCraft AIM LCR ONE 5" speakers

Thanks for the suggestions,
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