Yeah, its an electric valve that bypasses the throttle body. I notice that it gave the motor gas when it really didn't need to. When you let off the gas, this valve opens up and won't let the motor slow down right away and stuff like that. Mine's a 5 speed and I noticed that if I shifted to nuetral while the car is moving that the rpms did not go down to the normal 700-800 range but stayed up around 1200 until I came to a complete stop, then it dropped. I have this plugged off, so now when I let off the gas the rpms go down to the minimum idle speed. I have a manual choke cable that I use to give me a faster idle if I want it. I use this when I first start the car, then push it back in as soon as I get going and by the first light I come to it idles just fine(used to still be faster than normal until it got warm). It helps maybe 1 or 2 mpg from what I used to get depending on where I am driving. Going to work I do about 50/50 highway and city type driving and the average is about 26. Straight highway is 28-30 but I know I could do better if it had a higher differential gear. It does way too many rpms on the highway.