how beneficial will it be to block the egr?for example will i get better milage, lower egt's,ect.

I'm not positive, but I don't think it improves your mileage. What I do know is that it blocks that nasty soot from recirculating through your motor when the egr valve opens. A lot of people hve had problems with egr valves getting sooted up and getting stuck. A blocker plate eliminates that problem. I hope this helps.

You engine will be better off. You not be reburning the dirty air. Your engine will get the fresh air. Your oil will stay cleaner. You might get a slight increase in mileage & you will not have egr codes with the finger stick. Block it & do not worry about. My gm mechanic told me to do it. They are having so many egr failures. They can not keep them on the shelf.

I just put my blocker plate on today. I have been having issues with boost and that was the problem. Some siad it didn't matter others said it did. All you have to do is log a run and watch the EGR pos. and it will blow open under boost.

Although if you dont rerout the PCV, you will most likely have oil seeping out of the EGR. That was the reason I pulled mine. Now that I have a tuner, it smokes a ton! I need to block it again...
Jerry

Do they help with Perfomormance at all?

I would block & finger it for sure. You might not need to finger it if you still get the banks, but block it. It will help your motor life. I have not done the pvc, but I think I am going to have to add that one too.

what do you do with the pvc?

Its pcv (positive crankcase ventilation) not pvc (poly vinyl chloride). If you look in the diy section there is a good description of how to re-route it so the oil does not go into your intake.

My helped a lot, you know how your truck has good days and bad day and good kickdowns and bad ones? I run the hot+2 which is a smokey tune and a % of that is recirculated and that means bad air fuel mixture. I got rid of about 80% of the smoke at WOT almost none now. Before I could clear a 4 lane highway. Its faster too fell more confident throwing down. Also shifted better cuz I think towards the end of a gear there was so much damn smoke I think it bogged it down and now it snaps off quick fast shifts. That what I have experienced