Plenum head

[timshap]

I have just removed the head section to find the trumpets quite dirty inside with deposits and oily at the base etc.. should there normally be such a build up towards the back nearest the stepper motor outlet? it was fairly sooty.
Having cleaned out the whole thing the car/engine felt much smoother and felt as if it pulled better..
Should the trumpets and inlet manifold be cleaned regulary it isnt a service job though!!!
Views all please..