Yes, my prints have always been muddy and I'm beginning to realize it. So it's likely my fault. And my agitation is very soft too, I agitate two times, gently, every minute. So it may also come from here. Anyway I prefer increasing the dev time rather than changing agitation, it became such a habit that would be harder to change.
Btw, I also tested the exposure, and I'm seeing a fog on the supposd zone 0, at 100ASA. By how much would you increase the ASA rating ? I must admit that I don't want to bother with thirds of stops and skip directly at 200ASA...