Right then.
Purchased a new Gastester from Halfrauds today and gave em a go.
Idle knob all the way out idle was 1000-1100rpm
As they were I had front bypass at 1.5 turns out and rear 1 turn out both trim pots @ 12 o'clock.
CO for rear cylinder was about 6% ish and CO for front was over 10%!
Now...