The set I bought from Summit have one way check valves that screw on right the included pipe that gets welded in at the header collector and so far I have never had a problem with pressure going backwards. The included pipes that got welded into my headers were notched and cut at the proper angle so they went through the perfect amount and proper angle to "suck" or "draw" the vacuum properly. There was no guesswork to it. And the weld has held fine so far without the need for any other type of support brackets.
The only reason my breathers blew out was because I had the evac hoses disconnected to try some different exhaust configurations. The reason I am going to the welded bungs with threaded fittings is for peace of mind, a cleaner more professional look, more clearance under my cowl and if I want to upgrade to a pump in the future I will already have that part covered.
Again, I hope that whatever you decide to do works for you. And I liked the post because I am always wondering if I should/if I shouldn't go to a pump so I like seeing the other members replies and reasons why they are for or against pumps....
Have a good one!