It might help by understanding what dealers and distributers are held to by the manufacturers setting pricing rules.

MAP is the “minimum advertised price” for a product, as established by the brand. Any public posted pricing is controlled by the manufacturers. The minimum advertised price is technically not the lowest price a retailer can sell a given product for—it’s just the lowest price they can publicly display.

So, it would be in your best interest to contact the people selling the headers or certain parts directly for more information.