I am thinking about the cooling around the exaust to.
I designed it that way it is at the moment manly to make it easier to cast.
On the previous casting attemps of me a was able to get good result even to wall thicknesses as low as 2mm's.
I was thinking about welding on cooling fins to the exaust afterwards.
But I will probably do a re designe.
I am using to 2 exaust port designe for two reasons.
1. Cause its easier to cast and when done correctly I should get more blowdown. But i am not sure about that.
2. Auxiliary exaust ports should have a higher power output potential. Mainly to to faster blowdown flow in the Auxiliary ports thats why I kept the exaust port bottom pretty far up and keep the size of the exaust opening quite small (80% of port area)