The horse is dead

If they were a direct fit then they would not require any accommodations to get them to work.
Did they come from the packaging, bolt in place and fit like a stock setup?
No, they didn’t. The OP has a valid point.
How can you be so clueless to not see this? Do you really think that a guy should expect for everything to require additional work to install it?
Screw that. He had no warning. A simple WARNING next to parts that are not a direct fit would separate the hacks from the techs.
Know your market. He isn’t just selling to professional racers and engine builders.