S Tier

Performance TunePerformancePerformance Tune is the most universal upgrade. Applies to almost every bike.

A Tier

Race FairingVisual + AerodynamicRace Fairing swaps the bike's profile for a sport silhouette. Aerodynamic effect is small but visible.Sport ExhaustPerformance + SoundSport Exhaust swaps the exhaust note and adds a small power bump. Cosmetic and functional.Tire CompoundHandlingTire Compound is the most important handling upgrade for newer riders who slide out in corners.

B Tier

Custom PaintVisualCustom Paint is purely visual. Many limited palettes ship with seasonal codes.

C Tier

License PlateVisualLicense Plate is a free cosmetic that lets you put a custom tag on your bike.