Just starting the Armstrong Pullup Program. My max is already 20-25. Should I still start with bodyweight or should i add 5kg’s?
Definitely add weight if you’re just going to stick with Armstrong.
Rule of Thumb
Great rule of thumb is to increase weight per rep if you can do over 12 reps a set. Increase the weight until you can’t quite get 8 reps per training set.
So once you work up to 13 or more reps in one set, put enough weight on a belt (or even in a back-pack) so that you can only do 5-7 reps. If your max set is 25 pullups, your training set will probably be high enough to start adding weight.
Since you’re so strong already, you should consider switching soon to the Armstrong Advanced Pullup Program