I want to dyno tune my car, but first I want a converter so my question is. If i get this converter before my dyno tune will that change anything?

 

In terms of engine tuning, no it shouldn't have any effect. But you might want to wait for the tuning because some transmission tuning is always a good idea with a converter, if practical. Better and cheaper to get it all done at once.

Shift points, torque management, etc.