You buy wins, not a rank
Win boosting delivers a set number of competitive victories on the account and playlist you choose — you name the count, your booster plays until those wins are on the board. There is no target tier: your rank moves only as a side effect of winning, and where it lands depends on your current MMR, not a destination we promise. Because Rocket League has no promotion series and every result nudges your hidden MMR, each win tends to add a small amount of rating — community trackers put a typical ranked win somewhere in the region of 8 to 12 MMR, though the real figure swings with your win streak, opponent MMR and how far your visible rank sits from your true skill. Treat that as a rough range, not a guarantee: what's guaranteed here is the win count you order, not a fixed MMR total or a specific rank at the end.