Hey I was browsing online and saw a few adds for somethin they called a Twister claiming this piece of metal(or at least looks like metal) once placed in your air intake will increase you speed and give you better gas mileage.  Is this BS or really true?  Anyone tried it before on here?

Here is what the ad said:
"When the Twister is installed in the air intake of your vehicle, the incoming air travels through the twister and produces a vortex.  Air moves quicker into the engine when this is done.  More air into the engine means the fuel burns better and stronger, SAVING YOU GAS.  Tests have shown up to a 33% increase in MPG.  And have also proven 20 HP gains."

Think about it... it's something that's blocking the intake of air. Regardless of whether or not it spins, it's going to reduce the amount of air that gets through, which will reduce performance. Their tests probably consist of a leaf blower forcing air through it

its called the tornado and consumer reports tested it and showed it decreased power and gas milage