Here is a nice review of the valve.
www.vintage-mustang.com
I put one in a while back when I was running the Holley. It made a huge difference. I am still using it with the efi.
This is a must in my opinion with any modified engine. Most people try and chase down carb or ignition problems. When in reality it is the incorrect valve being used.

ME Wagner PCV Valve - A semi-brief review
Hi all, It was Jane's 55th birthday the other day and I'm insane so I bought my car a birthday present because I felt that if I didn't, it would come back to bite me in the ass. This year's gift: a ME Wagner dual flow PCV valve! In my defense, I actually was in the market for a new PCV valve...
I put one in a while back when I was running the Holley. It made a huge difference. I am still using it with the efi.
This is a must in my opinion with any modified engine. Most people try and chase down carb or ignition problems. When in reality it is the incorrect valve being used.