Chevy Trailblazer Fuel System Parts

I installed this Throttle Body Spacer on my 2002 Chevy Trailblazer. At first I was curious if it was even going to do anything. The installation was a breeze the instruction paper actually made since. After I put this product on you can hear a whistle sound, it sounds like a very small turbo. The Airaid product come to find out has made a difference. I have put it to the test with most of everything, when the light is red and it turns green you put the throttle all the way down it doesn't work. But when you have the throttle at half like going 30 mph then you put the metal to the peddle, you can feel and tell it works. Then when driving normally it does very well, the box says 4 mpg well lets get real now it does get only like 3 mpg better. The acceleration hp is all a little better.