Getting narced changes a lot from day to day...if you consistently noticed at 80 feet that yeah, you were narced, then I'd say though would be the level you could always expect it at. But it does change depending on how hard you are breathing, how cold, how deep, how dark...lots of stuff.
As far as if it's your limit or not...that'll start one heck of a debate!! Some will say it's fine, you can go a little beyond that, others will recommend you become a full tech diver before going beyond that. Recommendations may lead to flame wars
My honest opinion - don't push it. If you feel you are narced and you know you are narced...don't go much farther. If you are messed up, you are not able to react to problems as well. But it's definitely your own decision to make.
As far as if it's your limit or not...that'll start one heck of a debate!! Some will say it's fine, you can go a little beyond that, others will recommend you become a full tech diver before going beyond that. Recommendations may lead to flame wars
My honest opinion - don't push it. If you feel you are narced and you know you are narced...don't go much farther. If you are messed up, you are not able to react to problems as well. But it's definitely your own decision to make.