The as cast wastegate hole in the turbine housing should measure close to .900" right now. Typically people would open this hole up to 1.12" 1.15" leaving about 1/16" for the puck to seal against.
See this picture reference.
You would need to establish a better witness mark on your turbine housing before porting, as there is too much carbon build up to actually see where your puck falls / covers the hole. You have a witness ring on the actual puck, but that doesn't help up. It just shows where there is potential for a leak, not where you need to port. Also, keep in mind, that because of the bolt hole size in the downpipe, the pipe can physically be moved slightly with the bolts installed but loose. This can also affect the actual placement of where the puck falls.
The method I've used is, put some marking compound, shoe polish or even grease on the puck face. Bolt the downpipe up and tighten the bolts. Now, use a scribe to mark the downpipe flange and turbine housing straight across. These will be alignment marks that will help you when you re-install the the downpipe. This takes the bolt hole slop out of the equation. Once installed, slap the puck to the housing. Remove the downpipe and you should have a nice witness mark on the face of your turbine housing. You want to port the hole so that there is at least a 1/16th of an inch ledge that the puck can seal on. The hole does not need to be perfect, but you do need a lip that the puck can seal on. This is very critical as not ported correctly, the puck won't seal and you will have severe turbo lag.
Also you can port the inside edge of the hole, removing the sharp ledge that's on the inside of the wastegate hole. The lip that's closest to the 3-bolt inlet flange. See these pictures.
Hope some of this helps.
Patrick
