• Converting to Vent Line Extensions
• Converting to Filtered Vents out of the Air Cleaner

There are many aftermarket and homemade breather vent relocation mods available to move the vents out of the air cleaner.

There has been debatable ways to route the vent lines off the heads when doing air cleaner mods.
However, exact line routing comes down to function over fashion.
While it may look better or cleaner for the lines to be routed above the air cleaner;
Doing so doesn't make for good functioning of the breather system.

The air / oil that gets blown out is a combination of crankcase pressure and engine blowby.
Blowby gasses produce a corrosive vapor which doesn't need to go back into the engine.
It'll simply pool in the heads / vent lines.

As you can see from the drawings below, expelled air leaves the rocker boxes by running downhill to get out the vent holes in the heads.
If the vent lines are piped above the exit point in the heads, oil out of suspension will not drain back into the engine.
The oil would have to run uphill to get from the heads to the rocker boxes and into the lower end.
So there is no functional advantage to running the lines higher than the head vents.
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The air coming from the head vents has fine oil mist particles in suspension with it.
When that air cools, the oil mist falls out of suspension and collects in the vent lines.
Pointing the vent lines straight into the A/C (OEM) or down into a catch can allows the oil out of suspension to leave the vent lines.
However, pointing the vent lines upward of the head vents allows oil out of suspension to collect in them.
Once there is enough liquid oil in the upward breather tubes it will act just like the trap under your sink.
It may block air from getting out until the engine (on startup) builds enough pressure to push the liquid and bubble up to the top.
So it may affect crankcase pressure slightly until the lines are cleared.
Or the trapped oil may simply be blown out the vent lines in globs.

Vent lines mounted low allows oil to leave the heads.
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Vent lines mounted high tend to promote a mixture of oil and condensation settling near the head connection of the hose.
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Crankcase pressure was increased in 2004 by several means.
One of which was the reduction of the hole size in the breather bolts on the engine side (more restriction).
The smaller hole creates higher pressure in the crankcase on piston downstroke which aides in oil scavenging.
They also allow the air to leave the vents at a faster rate.

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Aftermarket breather bolts have a larger hole in the bolts.

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