What does upgrading your fuel system actaully do? I've heard about the air/fuel mixture but i'm not really sure what it is. Does it allow for fuel to flow through your engine, and if so, shouldnt it make your gas mileage go down quite a bit?

 

a fuel system upgrade is just like bigger injectors, larger bore on the fuel rail, high output fuel pump. It just makes it so you arnt gonna run lean and have all the fuel you need the more power you start to put down..