From my understanding....Hong Nor is a huge manufacturing company, just like Team C in China.
They do have designers and engineers, but that is to make any part, kit or accessories for X number of customers. My understanding is that if you order in X number of anything they will brand it, box it, label it a make it to your specifications.
With that being said, once they have your specs or design. There is nothing stopping them from selling your SPEC parts or design to anyone else.
Yes a majority of the IGT8 car is made by Hong Nor, but not 100% of it. IGT8 uses several manufacturers throughout the world including the USA to make their parts to IGT8 specs and complete a kit. This is to avoid anyone company being able to rebrand an identical IGT8 kit.
Btw Evil Knievel toy worth some $$$ now.