In addition to using our all rubber 2-ring type positive valve stem seals, the vacuum produced by Negative Pressure Supercharging is so powerful the intake valves MUST also use,
1) Our steel intake valve spring umbrellas, and
2) Seal the gap between the intake valve stem and collets with silicone

This prevents an excessive amount of oil from being pulled into the cylinder past the intake valve guides with Negative Pressure Supercharging.