I bought my fuel saver from realityagent. After installing this product, I can see my Apexi's air/fuel ratio meter reading has already changed. Now still testing it on my car to see further results.
Quite impressed because it does show some effect in the air fuel ratio. If anyone else has any air/fuel ratio meter, you could try it out and test before and after.
Cheers... will later buy from you (carrera), to install another unit to test the results.