What is this part?

I notice this part makes a whirring sound whenever I start my truck but subsides after a minute of running. I assume it's some sort of EGR but I didn't know my model would have that . For reference, I have a 2.7 liter I4 2007 access cab. As for the second picture, I see people saying taking this off and replacing it with a different pipe without the resonator box can increase airflow and horsepower but I've also heard the contrary, could y'all provide me a list of pros and cons and your personal experience with removing it if you have done so?

Thanks,
opolistika

 

Secondary air injection pump.

Emissions BS. Runs the longest on cold starts.

 

yeah DONT take it off or re-plumb it...its what Penguin said.

 

Thank you!

Just for informing myself, what does the resonator do and why is it important?

 

A Tacoma secondary air injection pump, injects oxygen-rich air into the exhaust manifold to help the engine reach operating temperature and reduce emissions. The secondary air injection (SAI) system helps the engine reach operating temperature and reduces emissions by injecting fresh air into the exhaust stream. This allows for a more complete combustion of exhaust gases