Had one, used one, threw it out. It is used for fine tuning, unlike the Pro-M model. You have to have some form of air/fuel ratio meter to use it correctly. It DOES NOT like moisture and WILL shut your car down. You end up pulling it out of line to start the car again.
That said, it does what it is supposed to...alter the voltage signal off of the mass air meter, and does produce noticable changes in air/fuel ratio at idle. However, that's about where it's usefullness ends. In the end, it "confused" my computer enough that my engine would run differently every time I ran it...very inconsistent.
so would you say that the Pro-M model would be a better one to go with? I hear that they have been improved. I want it so I can run a set of 30's or 24's (injectors) with my MAF thats been used with with stock 19's