This may sound very disappointing, but it is very difficult, almost impossible, to increase contrast and decrease density at the same time, with a same emulsion and exposure.

Benzotriazole _may_ *slightly* increase contrast, but it only do so in the very lightly exposed areas (shadow in negative, highlights in prints) and not in the rest of the curves. If you use too much benzotriazole, what is most likely to happen is to require longer development time and/or greater exposure, without changing the curve shape much except for the toe region.

Crawley did publish interesting formula and his commentaries on them. I have tested a number of antifoggants, desensitizing dyes and KBr in various contexts, but in my experience none of them is a magic bullet. The reality is that if you try to change one thing and you lose something else. In almost all cases, I got the best results by balancing the developing agents, sulfite content, and the pH, while keeping the KBr and other antifoggants well within the reasonable and normal range. In particular, I did not find any magical effect in using Pinakryptol green, Pinakryptol yellow and various derivatives of phenosafranine in developer solutions.