Vortec and K&N question???

When I installed the K&N performance air intake kit on my 350 vortec v-8
I have to remove the vortec unit connected to the stock air intake. What is that unit there for?

That black box is there to make air quieter so you can hear it. I took mine off and just cut a coke bottle in half and put it on so i can get direct air flow works good.