oil leaking from breather

I am having a fair amount of oil leaking from my drivers side breather. I have a breather on each of my Mopar Performance valve covers on my 383 with a Holley sniper system. The engine has just been through its first summer and while it ran well, I have had a fair amount of oil leaking issues. Valve covers at first were a bear to seal up. I added the breathers by drilling out the valve covers assuming I had too much pressure? Now oil leaks out pretty good. Wondering if I should use a catch can or something?