Originally posted by Austin
The unmolested wastegate opening. You can see how much area we have to work with by the shiny portion of the sealing surface.
My final hole ID was 1.078". I removed .092" of material from the lip - about 2/3rds of what I could've removed. In my case, the flapper door didn't sit exactly centered on the opening - it sat a bit toward the outside (toward the pivot point) - so I concentrated more on that side of the hole.
There is considerable room for improvement besides simply making the opening larger. I rounded all corners and edges inside, and removed all flow trips to make a very low resistance path for gasses to flow through the wastegate.
Nice post, d00!!!