Thanks gizzo
I did not talked about that because I forgot to take some pictures but I did some work on the exhaust header also.
As you saw it the exhaust port is enlarged at 35 mm. Then I machined a ring to receive the 41 mm header tube with 35 mm ID matching the port and 28 mm long (If I remember correctly).
Then I inserted a OD 38/ID 35 tube inside the header. All of this makes a constant matched 35 mm diameter from the head to approximately the position of the original lambda sensor (I reduces the bung protrusion inside the tube as much as possible).
Once again it probably adds almost nothing performance wise but it's nice to know it is looking clean inside
I read the discussion here about sleeves and anti-reversion
Did your AT work well ? What target AFR did you choose ? For me this map goes now from 14 for little openings/revs to 12.8 when WOT and high RPM.
I have yet to test it but you know, it's the winter this side of the globe