Disclaimer: Modding violates the terms of service of Gameloft. This guide is for educational purposes only. Install at your own risk.
A high-quality mod should be roughly the same size as the original app (or slightly larger due to unlocked assets). If the file is suspiciously small, it may be a "lite" version with degraded graphics.
Not all APKs are created equal. To ensure you are getting a high-quality version of Minion Rush 1.0.3: