VTT check valve

Not sure where to post this but I have a GT86 which has been supercharged and I am being told the following

Might be a good idea for all the people that are running boost to put a check valve behind the pcv valve and the crank case. I took the hose off and checked how easy it is for boost to leak out this inlet. There is no resistance at all and i could blow and suck air through this opening, should only be able to push air through but not come back.[img="https://www.ft86club.com/forums/images/smilies/iono.gifin my mind this means boost can leak out and into crank case[url=https://www.ft86club.com/forums/images/smilies/mad0260.gif]https://www.ft86club.com/forums/images/smilies/mad0260.gif[/url]Thanks to JAMESM who brought this to my attention with one of his old threads[url=https://www.ft86club.com/forums/images/smilies/thumbup.gif]https://www.ft86club.com/forums/images/smilies/thumbup.gif[/url] I am going to put a check valve in today and do a test drive to see the difference in boost pressure with and without valve. Might even put one on the brake booster line as i dont think it is a good idea for pressure to be going into booster then when braking, booster has to go back the other way when it is under vacume. Dieaframe is flexing one way then the other.please correct me if i am wrong[url=https://www.ft86club.com/forums/images/smilies/thumbup.gif"]https://www.ft86club.com/forums/images/smilies/thumbup.gif"[/url] alt="" class="inlineimg" style="vertical-align: middle; font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13.3333px; background-color: #eeeeee;" title="Iono" alt="" border="0" ]

Can anyone share light on this issue as I am told my fuel consumption will decrease if I fit this check valve. Don't understand it fully so could do with some expert opinion.

https://vargasturbo.com/product/vtt-billet-check-valves/?fbclid=IwAR391LEZTfq95jWNqwEs2HQ15bL9SYZISwH9LF-pXvg306XydAS72hsSQl8

Appreciate any feedback to explain this potential issue.