Bryant 2006 model 352aav-burner rumbling on low fire

[cougar123]

Bryant area Rep. from Bryant TEC service in the Chicago area, installed a disk in the outside air intake pipe near the inducer motor intake. He said it would cause proper air turbulence into the burner area. This stopped a problem I've had with this furnace since 2007 and 3 draft inducer motor replacements later!! ( no cost to me-warranty work) But a lot of unnecessary work by my local installer.
I have 2 questions;
1) did my Bryant model 90t, 352aav not have any of these disks in the first place?
2) what do they look like-I never saw the part before he installed it? cost?

Thanks

[George2]

Bryant area Rep. from Bryant TEC service in the Chicago area, installed a disk in the outside air intake pipe near the inducer motor intake. He said it would cause proper air turbulence into the burner area. This stopped a problem I've had with this furnace since 2007 and 3 draft inducer motor replacements later!! ( no cost to me-warranty work) But a lot of unnecessary work by my local installer.
I have 2 questions;
1) did my Bryant model 90t, 352aav not have any of these disks in the first place?
2) what do they look like-I never saw the part before he installed it? cost?

Thanks

It's a round stainless steel disk with small holes. I'm sure it had one but maybe it fell out.