A method includes: retarding spark timing relative to a predetermined spark timing when an engine torque output reduction is requested for a gear shift; estimating a first torque output of an engine based on N cylinders of the engine being fueled, an engine speed, an air per cylinder (APC), and the predetermined spark timing; estimating a second torque output of the engine based on M cylinders being fueled, the engine speed, the APC, and the spark timing. determining an initial pressure ratio across a turbocharger compressor; determining an adjustment based on M and the first and second torque outputs; generating a desired pressure ratio across the turbocharger compressor based on the adjustment and the initial pressure ratio; and controlling opening of a turbocharger wastegate based on the desired pressure ratio. N is a total number of cylinders of the engine and M is less than or equal to N.