Many universities in middle-income countries lack the peer-review infrastructure to assess research quality directly and instead tie financial rewards to publication in journals classified as Q1 under the SCImago Journal Rank system. By converting continuously varying journal quality into discrete institutional categories, these systems create sharp incentive discontinuities at quartile boundaries. In a pre-registered study, we apply a bunching estimator to 149,402 Scopus-indexed publications from Thailand over 2016–2025, exploiting Thailand's 2019 higher-education reform as a source of temporal variation. We find no significant bunching before 2019 but substantial excess concentration immediately above the Q1 boundary afterwards — a pattern not observed in Singapore, whose publication environment is not organised around explicit quartile-based financial rewards. The post-reform excess mass corresponds to roughly 1,575 additional publications over 2020–2025, implying an estimated 39 million THB in cumulative institutional expenditure. The findings suggest that quartile-based classification systems may redirect research effort towards threshold optimisation rather than research quality.