ok. Here is what I know.
-ZMAX has a lawsuite against them.
-A friend used it and says it works.
-The car can last a lifetime without ever touching any additives.
I wont use the stuff cuz its probably BS and the car has no use for it anyways. RESTORE is a popular product that actually works, but if the car runs better with it then it means you have problems with the engine and its only a temporary solution. MUGEN also released its own oil additive... that I would trust. (for hondas only though) Now if STi released an oil additive, then it'd probably be worth checking out.