So question 1. is it necessary to remove the air pump in order to install rb headers? I have a friend who's going to sell me his slightly used header at a great price but he said I have to remove the air pump to do so and if I do I'll have some idling issues just like he's 90s s5 fc.question 2 will I have idling issues? I have an 88 (s4) convertible and question 3 how much hp will I get (I don't expect much)

I've always wanted to buy rb headers but never realized that I had to remove some stuff to have them

no need to remove the air pump because of a header. If you still retain the cats, the air pump needs to stay. If the cats are gone, the air pump can go. If you remove the air pump, you should also remove the air control valve and get a block off plate.

http://www.mazdatrix.com/b-egr.htm
I can give you some more info if you need it.