I jad sort of jury rigged an old K&N by splitting it and sliding it over the fill tube in my C6.

I bought a nice replacement from the LS1 Speed and the same thing from PFYC.
It requires that you take off the coils and valve cover and the black fill tube etc.

I found out that if you just take the filter that comes with the breather and plug it into the black fill tube it has a nice compression fit. What is better is that it is baffeled somewhat to prevent splash from occuring. So now I have a filter that works; ahh, actually two.

I have driven the car over 1200 hard miles going to Ohio and back and haven't used a drop of oil. The filter stays in place and I know that I am not getting oil into the intake system.

I sent to K&N the oil filler cap for the car and told them what was needed to allow the hood to close and asked if they could make a breather with a molded bayonet fitting: that would be even better.

In the interim, if you want to stop the PCV from putting oil into your intake take it off, plug it up and just use the filter as mentioned above.