A long time ago before I really knew anything about tuning a car, I convinced my friend to trailer my DR750 3000gt vr4 6-7 hours away to have it tuned. This was after I worked my way through the install, tested the sensors and boost leak tested the car. It was a reputable shop that I won't mention here. Upon arrival the car was not making the power the tuner thought it would. So he did the best he could and I left $600 poorer with a car I wasn't happy with. The car didn't start that well and I knew my car was capable of more.
When I got home I posted my experience online assuming something was drastically wrong with my car. Using advice from the forums I boost leak tested again, I checked to make sure my cams were installed right, I rechecked my timing marks, I redid the timing synch in AEM etc.. Finally another tuner on the forums asked for my calibration file. I shared it with him and he was surprised with the tune I left with. He said it didn't even have knock feedback enabled.
With no one else to turn to in my area, and not wanting to transport my car hundreds of miles away again, I did just what I did with window tinting; I learned myself. About 10 years later my 3000gt is still on the road. I don't have official dyno numbers but I ran 11.5 @ 126mph in the 1/4 mile with a 1.89 60'. Now I'm tackling my Supra myself, and this time I'm videoing the entire process. That series can be watched on my youtube channel. Here is a link to the playlist. I'll embed all the videos as well.Tuning AEM V2 EMS On my Supra Playlist