I would call them medium output compared to regular strat pickups, I have another guitar with a YJM Fury in the neck and a Bareknuckle Slow Hand in the middle and the Fury is considerably louder. I have a Bareknuckle Rebel Yell (full sized humbucker) in the bridge of that guitar and the Fury matches it pretty well tone-wise.
The amp model I'm using is a Carol Ann Tucana, not a Marshall and to me it seems to have more gain than a typical Marshall. I can definitely push the gain further but for me I like the tone I get from it with the current settings. I'm not trying to match YJMs tone really, I want a sound that sounds good to my ears first and foremost. Too much gain to me just makes everything too compressed and kills the dynamics in your playing. Totally subjective of course, everybody has different tastes