These layshafts for performance engine/gearboxes as the standard type would flex and resullt in the breakage of the bearings causing seizure. Produced in an upgraded material and heat treated to the correct core depth they are a must in any straight cut gearbox or helical type where the engine has been tuned. The price of these although quite high is far below the standard type from the OE manufacturer. For 4 synchromesh.A Plus mini gearboxes only with 3 step type layshaft.