Need to replace the counter a/c vent box. Any ideas?

[gotjeepzj]

I’ve done some calculations and I need to install a bigger vent and air return for my bigger a/c. Any idea what I can mount here that’ll look ok?

[redsky49]

A bigger version of what you already have? Look at MSI Marine Registers and Grilles.
Multiples of what you already have?
Return air doesn't necessarily need to be ducted, as long as it has a path back to the coil. Don't run through battery box or something foolish. The return air will find its way back to the unit.

[gotjeepzj]

The return air is straight forward. I’ve found a bigger grill just need to make the hole bigger. I’ll check out MSI, thank you.