Product Overview

Upgrade your Audi S3 8P / 8V with a premium, track-ready brake system: the XC3 BTCC Big Brake Kit featuring nickel-plated AP Racing CP9660 calipers, CNC-machined alloy bells and carriers, 368 mm rotors, braided lines and all required hardware. Built for performance driving, club racing, track days or performance street use — delivering robust stopping power, durability, and consistent braking under high load.

Kit Contains:

XC3 Engineering custom anodised rotor bells
XC3 Engineering custom anodised caliper brackets
Chemi black bracket hardware
2x AP Racing 6 piston Pro 5000 series R calipers CP9660 - Nickel Plated
Braided brake lines
2x AP Racing Bobbins kit
2x ex-BTCC 368mm x 36mm rotors
Ex-BTCC brake pads Raybestos ST45 (Project MU H21 also available please contact us)

The BTCC rotors are previously used components. AP Racing do not offer this rotor size for public sale, as it is exclusively provided to BTCC teams. The rotors we supply have been used during a single session at a BTCC event and have undergone inspection to confirm they are in proper working order.

Pads are also used items, this again keep our kit as cost effective as possible when replacing considerable parts.

Raybestos ST45 & Project Mu H21 comparison

Attribute	Raybestos ST45	Project Mu H21
Pad Compound / Material	Mid-to-high performance racing compound, established racing pad material.	High-end carbon-ceramic racing compound, competition-only spec.
Intended Use	Endurance, heavy braking road-course racing, clubsport, track days — good balance of performance and rotor/ pad wear.	Motorsport / racing: GT, road course, short-oval, high-demand braking environments; “competition-only” pad.
Operating Temperature Range (Rotor)	– 700 °C	200 °C – 850 °C
Friction / Bite & Brake Feel	Consistent, predictable mid-to-high friction — good modulation and stable performance under repeated heavy braking.	Very aggressive, track-optimised friction; strong bite and fade resistance, stable through high heat cycles.
Rotor / Pad Wear & Rotor Friendliness	Lower wear rate compared to aggressive race pads; relatively rotor-friendly - a good compromise for clubsport/use with repeated calls.	According to manufacturer - “very kind to the rotor,” even under high stress braking, despite high performance.
Use-Case Strengths	- Clubsport/track-day cars that also see occasional road use - Situations needing consistent, repeatable braking under repeated heavy use - Good balance between performance & maintenance (rotor/pad wear)	- Full-on track cars, racing builds (GT, Time Attack, sprint, oval) - High-heat endurance or repeated hard braking - Builds where maximum braking performance is required and pad/rotor wear is accepted as part of use
Trade-offs / Considerations	Slightly less aggressive bite than “pure race” pads — may be less dramatic initial feel in very aggressive braking; but good balance overall.	As “competition-only” pad — may be noisy, dusty; cold-bite may be less predictable; less ideal for regular street use; pad/rotor wear may be more demanding.

Fitment:

Audi S3 8P / 8V

Please note these kits are made to order. We aim to keep everything in stock but some items may have a lead time. Please contact us for availability.

Purchase Replacement Rotors → View Product

Installation to be carried out by a trained professional or Warranty can be void.