The Booster is an upgrade for Tails' Cyclone in Sonic Adventure 2. It is a pair of rocket engines that can be equipped on Tails' Cyclone which enables it to hover across gaps. This upgrade plays an important role in later stages and missions. It is the equivalent to Dr. Eggman's Jet Engine.
This upgrade is found in the Mission Street stage. To get the upgrade, proceed through Mission Street until encountering a large gap in the road that can't be jumped across with a line of rings. Turn around from the gap to find the Booster on a platform behind a small road. Be careful when getting it as the road will collapse, requiring you to fly after you pick it up. Fly over the large gap to continue on with the level.
- If the player knows of the bridge being destroyed over the Booster Upgrade they can hurry and run across and clear the bridge before it falls. This would allow them to skip the Booster upgrade, this however makes the remainder of the level extremely hard unless you know of the shortcuts that bypass parts that require the Booster, like the Dash Panel underneath the bridge. It also makes any future levels which require the Booster impossible to complete.
- Oddly, Tails needs the Booster to hover, even though the Cyclone had used the jet engine from plane mode to fly to the barge where Tails fought Eggman.