BMW Mini Cooper S /JCW R53 Ported cylinder head. Designed for fast road use, this head gives maximum torque and power while still keeping all the reliability for everyday use. Giving smooth power and good economy. Once the valve guides are removed, over 25 hours of fettling and reshaping is carried out. The inlet seats are increased by 0.5mm and exhaust seats by 1.7mm giving the correct valve to seat ratio for power/flow. Exhaust ports are the main area of work with a large amount of metal removed from the'strangled' throats, which gives optimum performance while still using standard valves and springs. The guides are replaced and the seats re…