No squealing at idle doesnt mean it moves the volume of air it should, that is only 800 rpm and has a reverse function at idle as it does at WOT. When engine vacuum reaches 0 and from there on into boost the air gets drawn through the entire passage and is pulled in with the incoming air through the throttle body. It seems to work fine because nobody knows there is a problem IF there is a problem. Who honestly puts a pressure gauge on the oil cap and goes for a drive? Blowby is something every engine has, these engines use narrow low tension oil control rings. Spinning a higher rpm and adding more and more boost creates more blowby. Circle track engines run two larger breathers, one on each valve cover to allow the crankcase vapor and pressure somewhere to go or it will cost HP and put stress on oil seals because it wants to go somewhere. This is one reason serious guys use a vacuum pump to maintain vacuum in the crankcase to prevent this from happening. Trying to squeeze crankcase pressure at 6300 rpm with 10+ psi of boost in the intake through a puny 1/8" square hole with sharp turns is not the best way to let the pcv system work. Look at the size of the hole in the intake that meets up with the blower housing in stock form. It is an easy solution to not run a breather and is a clean setup but is not large enough to do the job it needs to do. When the hole is blocked off or gasket collapses over time to fill the hole then you have a lot of vacuum on the crankcase and it is going to drink a bit of oil and give you your squealing noise. Almost all factory PCV systems use no less than 3/8" or normally 1/2" diameter pcv lines in this end of the system. Revving the engine much higher than stock and adding more boost then necking down the pcv passage that must freely breathe isnt the answer, but again is a convenience and something nobody worries about.
