Blocker plate will throw codes. EFI LIVE can shut it off without the blocker plate and it will run perfect. Blocker plate will only help when the boost hits over 20 psi and it causes the valve to kick open.
Go with the blocker and finger stick if you don't wanna go to the complete delete. I ran a blocker and finger for a couple months with no issues. Have since upgraded to full delete. Also went to EFILive and highly recommend it. What a difference.
LB7 Don't have an EGR. Duramax didn't install EGRs until 04.5 with the LLY. LB7's have no emissions
There were lb7's that came with emission control on them. I read it was the lb7s that were built and being shipped into states that had smog control n all the regulations. California was a big one. I have an 03 lb7. No egr. A buddy of mine had an early 04 with an egr on it. He just did a full delete on it. Worked pretty good for him. But he ran it in the 1/4 mile more than on the road.