The drilling process is obviously poor and the results are not consistent or reliable. I have been able to tune a number of them to show a correct overall air fuel ratio, many are not tunable at all. Myself or anyone that tunes with them is only getting an average reading, some can be richer and leaner and they can be close enough to still seem ok, this does not make them safe and I strongly recommend to not use them. This is my opinion based on my experience dealing with lots of cars that have had huge issues that changing out the injectors fixed. The more that I am having to deal with them, the more I am surprised others sell them.
