So I'm buying the stillen cold air box and it will be coupled to the my z-tube. I was looking through an old thread and someone commented that an ecu reflash is required upon installing the stillen. This isn't true is it?

not a reflash, but if the SES light comes on, you might want to reset the ECU.
-GP-

You are good to go. If so desired, simply reset the ECU via the pedal method. Enjoy your new mod.