now imagine not to have any vent , with the shield attached is good and protects a little bit from rain+snow.

 

The way the fins are angled on the shield is for minimal rain to enter in the engine bay while driving. Because when you drive the rain will hit the shield at an angle and the rain bounce right off. It also lets hot air exit more freely, it won't hurt having it off but think about it why would they put one on there anyway, and personally I don't like the fact that people can see right through it and see whatever mods you have under there, I like to stay as stealth as possible. Just my .02

 

leave it on cause its lets the hot escape better with it on

 

i never ran mine. i have a lot of time put in under, screw it gotta show it off.