I don't know about the specific people who posted here, but several years ago, I did look over some cars that were tuned by a shop that is no longer in business. I remember seeing two tunes that were running very lean and experiencing a good deal of knock. One was a bugeye WRX that was running lean and pulling up to 10 degrees of timing due to knock. That owner ended up starting a ton of drama over the issues he experienced with that shop. The other was an STI that I ended up re-tuning for the customer and haven't heard from since.

I may have looked over logs from some other cars but I don't recalls the cars or the owners specifically. Remember, just because the tune is bad doesn't mean the engine will blow up... especially if the owner doesn't drive the car hard too often. The factory ECUs are great at protecting the engine even under poor conditions. The dyno and a/f plot that Paul posted in this thread is a perfect example of that. That doesn't mean, however, that its ok to run around on a lean tune and just let the ECU pull a ton of timing to try to save the engine. Give a tune like that to someone who actually tracks their car on a regular basis, and the motor will not last long.

As far as picking someone to tune your car, I would recommend looking through reviews and speaking with people who have actually personally dealt with and been tuned by whichever tuner you're considering. Many people will offer their opinions about someone without ever even having met them in person, let alone been tuned by them. Individuals who have actually had work done by someone will be able to provide a much more accurate opinion based on their own actual experiences.

Thanks