in 2002 we had our 1st alloy Aston Martin DB2/4 head ported by Motorman, he tapered the port out to the same size as the manifold, we never got great power of that head whatever engine it went on, whatever cams we ran.
In 2004 or 5 we had another guy port our heads, ex Cosworth, he tidied the exhaust port but left the step in as he said it was worth over 10 bhp, he was right, same spec engine, same inlet airflow, little or no improvement in exhaust flow but 10 + bhp up on a 2.9ltr 6 cylinder.
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