When valve speed increases by high rotation-ization of engine, or 'Jumping' may occur by the factory valve springs.
Also, since inherent pitch is low, 'Surging' may occur in a high rotation region. In Jun's version, the valve spring, with which the load is optimal at the time of a set, and a valve lift was manufactured. Even when the amount of valve lift increases by using a high cam, since the adhesion margin is secured enough, the Jun valve springs does not have degradation and its durability is also improved.
For Evo Models I - IX.
Stock images used. Actual product may vary.