So I read some site about a Pair Valve mod on the F4Is and even showed a DIY. I searched on here but couldn't come up with any threads.

I want to know the benefits and more so the negatives... Anyone?

 

Alright well the only benefit that I can see is keeping warm dirty air out of the airbox which has everything to do with the pcv system and not the PAIR valve. The pair valve runs fresh air from the airbox through the exhaust ports to burn hydrocarbons for better emissions. However, when the engine is under load the PAIR valve closes so this system only works at idle. Linking the pcv into the PAIR system would essentially not allow the pcv to vent under engine load which is bad.