I sold a customer a tuff country performance lift.
They got the kit with no coils. Tuff Country lists the kit part numbers along with the coil part numbers, but they don't mention that the coils aren't actually in the kit.
I simply ate the loss and immediately shipped my customer the coils and learned the hard way that Tuff Country doesn't include coils in the kit.
Then, the customer went to install the kit and the bushing and hardware was missing from one of the extended radius arms. I called Tuff Country and they shipped the missing parts directly to my customer.
Ultimately, it's my fault as a dealer for just assuming the coils were in the kit like EVERY other manufacturer includes them.
That was just my experience with their performance kit. I had to readjust my price so I don't lose money again. I may even dump their kit altogether if the pieced prices make it to unreasonable.
Bottom line, it would have been easy for me to pass the blame off on Tuff Country, but if you understand how they sell their stuff, you can price/sell it accordingly.