I have a berk header with a dent on the one of the down tubes. How might this affect performance?

 

It won't affect it at all as it is so miniscule. The only time I would worry is if there is a hole in the header. I'm sure that dent is repairable. If it bothers you enough, I would take it to a muffler shop and see if they casn remove the dent.

 

I'm actually selling the header, so I want to make sure I'm not screwing anyone over.