I was thinking it is a check valve too but can't find solid info. For $60 it should be more than just a check valve. I'm going to put together a ball and spring version today and see if it works better.
Originally Posted by sonoronos
The missing link is the name given to a check valve that is designed specifically to bolt directly onto the Honda MAP sensor. I believe it is just a plain ol' check valve.
I think you need to use more than one check valve to perform what is called "boost fooling". I've seen Hondas set up with 3 check valves as opposed to one. Not sure why, but I think it's due to the fact that cheaper check valves leak.