"i'm trying to build my own Main's [sic] line filter"

I agree with Rob - Why?!
Not only will an off-the-shelf unit be tested & approved for safety, it will also have a well-specified performance
How do you intend to test your homebrew filter to verify that it is achieving the required performance?

"...max efficency"

What do you mean by "efficency" here?
Are you talking about energy losses, or filtering performance?