I really don't know to be honest. The stamp reads SX428T. It doesn't seem like a particularly lary cam as the car idled nicely. The car boosted nicely from really low down the rev range. It's my first experience of a Newman Cams camshaft but I was quite pleased with it and they appear to get good write ups. I did consider putting this head onto my new engine but the thought of spending another £80 for a Burton gasket put me off.