Well, my lumens/kcd before/after tests sometimes show no gain, sometimes show small gains, maybe 3% or so at best. I can't always do before/after because of the nature of the mod, accounting for changes in lens thickness's. I'm sure it has to do with the quality of glass you replace, maybe the change in thickness is a factor as well. There was an early thread on tests performed on these AR lens and they showed nice bumps. This thread is interesting for real world AR lens test results: https://budgetlightforum.com/t/-/19458.