Intake Air resonator is gone: replace or not?

It's a really easy part to replace and you'll be able to practice on a vehicle at a wrecking yard when you remove it. And I agree that its not an issue to drive without it, but using a wrecking yard to replace whatever is missing or broken will heavily influence your decision in the future when the car needs expensive repair work.

As in the people who give up on their vehicle when an expensive repair happens are usually the ones that don't fix all the little things or keep their car clean. Where as those who do that, will be more likely to spend for the expensive repair and keep their car on the road for years to come that because its only one expensive thing wrong with the car, not a long list of things.

 

This may become an issue during the cars' smog inspection; if the inspection station realizes it's missing. Missing pieces or aftermarket equipment under the hood, usually triggers a closer inspection. If there's a question, most smog stations will simply fail it - rather than place their license to operate in jeopardy.

I'd visit a junk yard and pull the entire assembly; just in case. It's just a couple of screws and clamps or have whomever repaired the car take care of it.

Good Luck....