Original Athena cylinder. The same sort of money that usually gets you a humble cast iron cylinder will buy you a plated aluminium cylinder here. A comparatively tame exhaust port timing together with a huge port area make for an extremely torquey kit which will also rev on nicely. There are not many cylinders powerful enough to stand the Pro's pace of the line. Thermal advantages of aluminium cylinders should be known by now, so what you get is a reliable cylinder with a strong asso piston, a set of carbon reeds and a choice of base gaskets to adjust squish clearance.