On my 3rd 2 week cycle of clen now, I start about 40ml/day and end up around 125. However at the end of each of the previous 2 week periods I found that even at 125 or higher dosages I barely noticed the clen working anymore.
Im VERY VERY tolerant to all sorts of stimulants and weight loss substances in general, but this seems to be along the lines of what a lot of other people say too.