Been to 152, looking (and finding) a school of hammerheads in La Paz. I was supposed to go with a DM but as we started going down from 110 another diver had an issue. I was a bad buddy and did not check to see where he was, and a minute or so later I was at 150ish alone. Mr. hammerhead came right at me (i was breathing very, very slowly, barely moving, just hoovering, and my reg was stuttering), and when he got too close for comfort I exhaled and he veered away.. of course I had no redundant air and my 'puter was yelling at me. I made a 1 -2 minute stop at 90, and rejoined the group at 60 or so. we all went up (and I ended up holding on to a new diver who's buoyancy sucked and I helped him to not rocket up). back at the surface I had 1000psi left (started with 2900). divetime was 28 minutes.
although it was a stupid thing to do I felt very relaxed the whole dive (except when the diver I was trying to prevent from killing himself was thrashing around) and did not feel very narced. I've been more narced on 80ft dives. I was well rested and hydrated.
my reg was serviced a couple of weeks before and had been working fine it was probably working outside of its limits.
I've decided to maximize the amount of learning I can extract from any given action, whether it is a stupid one or a smart one. as such I have purchased a stage kit/bottle/reg as a result of that dive. I also am now doing a rec trimix course.