That is a completely different situation - you weren't modifying something, you built a fabricated kit and sourced an off the shelf turbo that worked well for the application. Anyone with a decent fab shop and a source for the turbo could easily buy one of your kits, use it to make jigs, and copy it. Or anyone could just buy the turbo you use and fab their own kit from scratch that would look a lot like they copied your kit, when really it is just that there isn't much room to get exhaust from the manifolds into a turbo and a downpipe out, and from an intake box to it and boost out of it to the intercooler they have no option but to make it the way you did.
Now lets say that you didn't tell anyone but you were actually taking a turbine housing that was meant for a small wheel and using a bigger wheel in it, but clipping that bigger wheel down and only machining the housing a little and at first look most people would think it was an off the shelf turbo. Most people would copy your kit and put an off the shelf turbo and wonder why they got different results. The guys smart enough to know to tear apart the turbo and measure everything and copy your cut profile and everything would be smart enough to have already been doing it themselves without copying you.