vacuum tube from the intake to the valve cover
 

Just curious, i've seen this done on other cars, but what is the purpose of that vacuum tube going from the valve cover to the intake piping? I've seen some just put a little cone filter on both ends (valve cover and intake).... Any ideas as to why?

its the hose from the pcv valve. small amounts of oil end up back in the intake manifold from this line. some use the filters you've seen and some prefer a catch can.

im sure someone with a little more knowledge will chime in and elaborate on this :)

It's the fresh air intake for the PCV. Most of the people putting a filter in place of the hose do so because they have added a aftermarket cold air intake, or FI setup of some type.

There isn't any performance gain from running the little filter. If anything it dirtys up the engine compartment from the oil saturated filter.

not talking about the pcv valve... I think the pcv valve is towards the back of the engine right? i'm referring to the hose that connects to the intake pipe itself, not the manifold, this hose is located towards the front of the car... U know, when changing your intake, there are 2 vacuum tubes that you have to connect to the intake pipe, 1 of them goes to the valve cover...

Same hose I'm talking about. That's the fresh air inlet for the PCV.

gotcha.