HPD oil catch cans / oil air separators prevent oil from entering into the intake manifold and mixing with the carbon from the EGR, clogging up vital components and potentially causing damage.
Modern 4WDs tend to have more parts in the intake manifold such as sensors and EGR valves that can malfunction due to the oil film produced.
The HPD direct bolt on separator kits are ideal for 4WDs running an intercooler or turbo kit and they come complete with mounting brackets, rubber hoses and hose clamps. The separators eliminate oil vapour that can contaminate the intake system and therefore helps keep the intercooler clean (internally). This translates into more efficient cooling and better power delivery from your engine.