I have tried a couple different ways of blocking off the EGR on my camaro and have found the best way!

Go to your local GM dealer and ask for part # 12558346.
Its $16.62, tax and all.

Here is a picture of it:

http://memimage.cardomain.com/member.../588367_44.jpg

I was going to use a rubber expansion plug, but had trouble finding anyone who carried one in 1 3/8. But I like this since its a GM part

 

cool, the only thing about that is an expansion plug is like 1.38 at advance auto. But thats cool its a dealer item, whats it normally to?

 

On the 6.0L trucks sometime people have braking problems due to loss of vacuum. Blocking off the EGR and removing it restore the vacuum, and the braking.

This is the part they use to accomplish that.

 

TTT people need to know about this

 

The plug is used to fill the EGR hole on applications that
don't have the EGR. Model year 2003 only a couple
engine types required EGR, so the plug is used in everything
else. That way the same intake mold can be used for
most applications.