i personally like a gsr bcause of the better quinch in the combustion chamber wich promotes a better burn when the cylinder pushes all the air/fuel into the wedge towards the center of the spark plug. a type r and b16 have a more open chamber design. if one had the money id recomend on a setuo getting gsr head and having a shop weld and machine a 4 leaf clover shape into the head and polish and deck it. super awsome quench areas= killer burn with lower carbon buld up.