: You cannot install a custom ROM without unlocking the bootloader. Vivo does not officially provide unlock codes, so you may need to use third-party tools or exploit-based methods.

Before diving into the list of the "top" ROMs, you must understand the stakes. The Vivo Y51 (specifically models like PD1948F_EX, PD1948F_EE, and the Y51a) is not as developer-friendly as a Xiaomi or OnePlus device.

Users who prioritize stability and pure speed over flashy features. 2. MIUI Ports (For the Feature Lovers)

Because vivo does not officially support bootloader unlocking easily, the development community for this specific device is smaller than that of Xiaomi or Samsung. Consequently, you will mostly find ports rather than native GSI builds.

Here is a useful blog post structure detailing the top custom ROMs for the Vivo Y51.