Recent empirical research has explored the hypothesis that fiscal disparities may lead to bias in yardstick competition between rent-seeking local administrators when voters are affected by information asymmetry. Allers (2012) argues that equalizing grants may correct this bias; Di Liddo and Morone (2017, 2022) conducted laboratory experiments to study the correlation between fiscal disparities, grants, and yardstick competition, considering only discretionary grants, revenue-based grants, and grants computed on the difference between fiscal capacity and expenditure needs. In this paper, we extend the analysis in two ways. First, we provide theoretical insights on the effect of equalization grants on yardstick competition. Second, we conduct a laboratory experiment that extends the previous analyses by comparing the four most common equalization formulas. Our findings indicate a clear inverse correlation between fiscal disparity and voters' rent detection ability, as well as a positive effect of fiscal equalization on citizens' ability to detect corruption, depending on the equalization formula adopted.