I bought a factory correct air box for ruby on Ebay. Her old airbox had been bubba cut for that deep throaty quadrajet sound.I also imagine the intent was it would be faster or have more power.
Ruby has always had several flat spots through the rpm range and general lack of pep.
After installing the new filter box all of these issues went away and thankfully a bunch of noise left too.

My butt dyno says the powerband is much more linear which makes it feel like I added a cool new carb and intake.

 

Nice.