After getting this, I decided to have a go at porting while it was all off.
Header Pre-port.
Both sides pretty coked up, 10 years worth I imagine.
Always get new ones, cheap from Japimportparts.
With the up pipe, got a real STi one with no cat. Much easier to get in and out through that bloody small gap.
Looked up a few images on Google, as long as you don't go beyond the ring of the gasket, its grind away. I took off a fair amount, and gave it a 45 degree angle as recommended. Smoothed it down as far inside as the dremel would go too, took the nasty burs off. One side has a big lump sat right be the port.
And to finish, heat wrapped the up pipe. To get around the CEL light error, which comes on instantly, like the airbag mod, a 2.2k ohm resistor gets plugged into the socket.