Ninja is for mulching. Most "standard" Snapper blades are of the "high lift" variety, intended to create a strong vacuum that lifts the grass to cut it, and then discharges the grass through the side discharge port or into the bag if so attached.
So are you mulching, or bagging is the answer.
And just verifying that we are talking about the old school Snapper mower with the disk drive, and not the Wal-Mart MTD rebadged mowers?