Originally posted by jayfotos
How does all that help?
The coolant hoses that run into and out of the top of the intake manifold circulate coolant through the manifold for warm cold-engine starts. It heat up the manifold (circulating warm coolant through it) so the engine starts better on cold days... if you live in a wamrer climate you may consider bypassing the manifold by just taking both hoses off the top and adding a "barb" or fitting in between (joining both hoses together). Some say you can gain a little horsepower this way... I think I feel a difference, maybe not.

The crank case expels a little gas back into the intake, which goes back into the manifold and engine. Adding a filter keeps the gasses from going back in... whether it helps of hinders, I don't know. You'll hear both sides, but I think many agree it is just cleaner.