What is it?
EGR valve
I removed mine, somebody makes a block-off kit, google it I cant remember where I found it...
I am running a aftermarket ECU (FAST XFI), so I don't know if you'll have problems with the factory ECU, i'm guessing the tuners/flash could delete it, since the kit is avail, also the 6.1 doesn't have it...
JOE