Tell someone 2.5K for a nice set of headers and they often look at you like you have 3 heads. Quality material and parts, keep them equal length within .5", make them fit, make them reasonable to get on and off, the handwork of the collectors and the inside of the tubes at the flanges, etc., etc. Any less and you are just doing it for a hobby.
If the results don't match the theory, change the theory.
