You don't necessarily "need" a dyno to tune your fuel map. You can record a full run on the street at full throttle, you just need your buddy to sit in the passenger seat with the laptop plugged into the car's computer to record the a/f ratio. Then you can tweak the fuel map and do it again.
the cost of the computer connectors and the reprogramming software is not cheap, either... And requires a lot of knowledge and technical know how to create a fuel map.