I can see that but I never tried. If it didnt fit the machine it didnt run. Was too much of a liability from a business standpoint. We still accommodated different wheel bases by unbolting the wheel clamp and moving to or fro on the slide. But if it still didnt fit no dice.
Almost forgot to ask, how did you interfaced the wide band from your pipe to dyno. The 250i is wide band capable and can be ordered with internal wide band option or have it installed. Typically a probe to "sniff" was inserted several inches in to pipe past baffles to get reading.