Originally Posted by CantRepeat
I'm late to the party on this and did not read the entire conversation. So if this has already been covered I'm sorry for a repeat.
It has been my experience that, if you remove the hose coming from the valve cover you must have a breather type vent. It allows the crank case to ventilate and if you close it off you will create a ton of back pressure that will sure blow out some seals. A lot of times those breather caps with no hose will spew out oil at higher RPMs.
Yes, if the flame areestor has a vent, you must replace it with one with a vent. You should replace with the same kind.
I got the slim down version without the vent as this replaces the one that was on the LT1 originally.
K&N 59-5020 K&N Flame Arrestor