what adverse health/environmental effects it could cause. I'm naturally skeptical in general, and feel skeptical that the effects would be noticeable. I have mine deleted and routed underneath the car towards the rear. I feel like the fumes don't have an easy entrance inside the cabin and most of the time the car is moving anyways. But then again, aren't fumes only a concern (with CC deleted) when either filling up at a gas station or when the car is not running since there's no engine vacuum pulling the fumes from the tank while running? I would think the fuel pump is creating a vacuum in the tank and sucking outside air in through the "vent" line while car is running. Maybe I'm wrong.
