is about 5/8 or 3/4 and see how much pressure you can build up with the turbos. I doubt you would get 2 psi of pressure. I added an additional 3/4 tubing before the TB on my application. A local Z er in Phoenix (PunkZ) had his egr block off with epoxy and penny's. One came off during boosting at 20 psi because he didn't epox it right. He lost ALL of his boost . He has TD05's. How big do you think that egr hole is? It is about 3/4 of an inch .