vents

Hello, I have a question regading a snorkel kit I just bought. I see it comes with check valves for all the vent lines for my Talon. I have read that usually gas tank and diffs need both directions to prevent vacuum and blow seals. anyone using this setup? Also their pioneer kit comes with...

Ok, so I have my OEM glass windshield inbound and wanting to modify it and wanted some opinions from others with this windshield. Would installing vents where the orange arrows be possible.....according to the listing a 3-1/4" hole is needed....is there enough room in either or both of those...