There is no "byte" in the SI. The question is therefore irrelevant. There's an IEC standard containing prefixes for 2^10, 2^20, 2^30 etc, and those prefixes are kibi-, mibi-, gibi- and so on. The SI officially references them, even if they're not strictly part of it.
"For a male and female to live continuously together is... biologically speaking, an extremely unnatural condition." -- Robert Briffault