Engine tuning relies on two major factors to increase power and torque, more air and more fuel. As the amount of air flow into the engine increases, more fuel must be present to maintain the correct mixture for the most efficient combustion. For basic tuning, the stock ECU and fuel system can detect the increased air flow and match this by increasing the amount of fuel which is injected into the engine. However the limit of the stock fuel system is easy to reach and further tuning without addressing the fuelling can lead to engine damage or failure.

HKS offers a range of fuel related components in order to allow safe high level tuning.