I (Somewhat) understand header design for N/A vehicles and the value of equal length and short vs. long-tube headers but how much of this relates to design for turbo headers?

Do equal-length headers create any advantage/disadvantage to spool, power, engine-smoothness, etc.? Does their apparent added length hinder performance?

Does a shorter distance from the exhaust port to the turbocharger create any advantages?

Are there any other key facets of header design I should be aware of?

I ask because my curiousity was sparked by this comment from another thread:

Thanks for any help. I look forward to hearing from some aftermarket turbo-kit vendors especially (As well as some of the more turbo-knowledgeable members). I just want to make the most informed desicion when I upgrade.