Mitch4t asked if any component manufacturer has gotten on board with recommending aftermarket power cords...
When shopping for an integrated amp last year ($4500 piece of equipment) I spent some time with a tech from the company discussing my speakers, room, and whether that particular amp was a good choice. After covering all the bases, he asked one last question...did I have any plans to purchase an aftermarket power cord. I said no, just planned to use the one that comes with the unit. His response, and I'm paraphrasing, was basically "good, don't waste your money".
It's just one anecdote, from one guy in the industry, but since Mitch asked...
I won't publish this gentleman's name, as I don't think it's appropriate, but I'm quite certain he's been in a position to test more equipment than I have, so his opinion carries weight with me. YMMV.
As a side note, thanks to my local dealer's in-home demo option I have tried various power cords with my ARC VSi55 (not the unit I'm referring to above, that's in another system), and I could never hear a difference.