Recently installed some Kahplenke brackets that fit 5.25” speakers in the normal 4” mounting hole.

Finished product, once I buy the second piece of this kit, should look something like this

these kits are NOT cheap, but in my opinion are the ultimate stealth upgrade.
also found I’m losing some mid bass currently with the bracket mounting situation, but if your aim is stealth and not strictly sound quality I’d recommend these.
https://www.bneshop.com/collections/240/products/240-5-25-speaker-bracket-and-grill