In many cases, stock jetting will be fine. However, as the motor is modified by using a good aftermarket pipe, camshafts, headwork etc, re-jetting will be required for optimum performance with our ignition. This would also be true without our ignition. If you have little experience in jetting, you should seek the advice of a qualified tuner or Dynojet Research, manufacturer of quality jet kits for the past twenty plus years. Failure to properly jet the motor can result in poor performance and severe engine damage.