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 X.
Stock images used. Actual product may vary.