Sits on the runner of the manifold between the tb - head. Diamond shape flange. 2 bolts.
It allows unburnt exhaust gasses to re circulate back into the intake stream and re burn.
Blocking it off means no dirty exhaust gas taking up valuable fresh air space in your intake.
I kind of figured as much =P More meant is there any real world benefit to removing it. I'm guessing there's a port specially in the head for it or something. Also, what Jazz9 said. Don't know if it would really make all that much difference to tuning, but still interesting. If it malfunctions, is there a chance that it could create a boost/intake leak or cause knock due to the hot/burnt gasses?