Many GR Corolla and GR Yaris owners eventually start looking deeper into their brake calipers. This usually happens after spending time driving on mountain roads or participating in occasional track sessions. In many owner discussions one phrase appears repeatedly: silicone high temp dust boots.
Whether your GR Yaris is still running stock calipers or already upgraded ones,
this Brake Booster + High-Flow Master Cylinder combo
delivers sharper, more predictable control across all driving conditions.
If you purchase the piston kit, you will receive the correct number of pistons, silicone dust boots, oil seals, and stainless steel bleeding screws (note: not available for some models).
Owners of early G-Class (2001 and earlier) face two issues at once: the original booster (OE A 002 430 99 30) is discontinued and used units are inconsistent, while modern usage—bigger tires, added weight, faster roads—demands more assist and better control than the old hardware delivers. The result is a heavy pedal, delayed deceleration, and...
Owners describe: "The usual pedal pressure no longer slows the car. I must press deeper and harder." Some hear a short hiss when pressing; it disappears when releasing. These are textbook signs of a booster losing vacuum assistance.
