AP Racing's part number:

• Disc: CP6565-228GA/CP6565-229GA
• Caliper: CP9451-2S4L/CP9451-3S4L, 4 pot, ANO

Complete rear AP Racing by Essex Radi-CAL Competition Brake Kit for the Porsche 987 (2005-2011) Boxster S & Cayman S, all 981 (2013-2015) Boxster and Cayman, except for GT4, and 718 Cayman S & Boxster S.

• Retains OEM parking brake functionality
• Eliminates unsprung weight from rear of the car
• Features AP Racing CP9451 Radi-CAL four piston calipers
• 340x28mm 60 vane heavy duty AP Racing discs
• Every component designed to resist the heat of extended track sessions
• Pistons sized properly to allow for seamless integration with OEM master cylinder and ABS system
• Designed to complement our front 986/987 Front Essex/AP Racing Radi-CAL Competition BBK
• Patented Disc Burnishing/Bedding Service with kit purchase $100
• Caliper Pad Tension Clips not included

What's In The Box?

• One pair AP Racing CP9451 Radi-CAL Pro5000R racing calipers
• One pair 340x28mm AP Racing CP6565 heavy duty J Hook racing discs, with fully floating 6061 hard anodized aluminum hats and attachment hardware
• One pair caliper mounting brackets and hardware
• One pair Spiegler Stainless Steel Brake Lines with abrasion resistant coating
• Detailed installation instructions
• Brake pads are NOT included with our system. Racing brake pads are a highly personal choice. Many manufacturers include a set of inexpensive, low quality pads with their brake kits. Rather than artificially inflating the price of our system with a set of pads you probably don't want anyway, we've decided to remove the cost from our system and allow our customers to choose the pads that best suit their needs/wants. When purchasing our kit, you are able to choose one set of front pads at a substantial discount vs. the retail price. Please use the drop-down menu to select your pads.
• Pad Tension Clips (frequently referred to as anti-rattle clips) are NOT included with our Competition Kits, but we do offer them as an option if you're concerned about NVH. One of the great benefits of the AP Racing calipers in our system is that they are designed to accommodate pads from a wide range of manufacturers. Each manufacturer builds their pads with specifications that are slightly different. As such, pads from different manufacturers, or even from different batches, won't always fit in the calipers in exactly the same manner. Some pads are a snug fit, while others may rattle around and produce noise. The Essex Designed Pad Tension Kit is designed to dramatically reduce pad movement inside the caliper, along with just about all resulting noise. 

Radi-CAL

“Radi-CAL” is a blanket term used to describe AP Racing’s patented asymmetrical brake caliper design. Radi-Cal technology is grounded in Computer Aided Design (CAD) and Finite Element Analysis (FEA), and allows for organic, alien-looking designs that are a radical departure from conventional caliper designs of the past. Radi-CAL's are widely considered the pinnacle of current brake caliper technology. Since their inception in 2007, these revolutionary calipers have amassed a lengthy string of race victories at all levels of professional motorsport, while redefining brake performance expectations. For more details on the design concept and what these calipers have achieved in professional racing, please visit our blog and read The AP Racing Radi-CAL Story.

The key benefits of the Radi-CAL design:

• Massive Stiffness Increase- A 30+ % increase in both static and dynamic stiffness vs. conventional calipers allows for far less deflection under load, which means superior pedal feel & modulation, more even pad wear, and longer caliper service life.
• Considerable Mass Reduction- Removing all extraneous caliper mass lowers the caliper weight, despite the huge stiffness increases.
• Optimized Airflow- Air moves around and through the caliper more efficiently, providing superior heat evacuation and cooling.
• Efficient Packaging- The asymmetric caliper profile and internal fluid porting allows the caliper to fit into tighter spaces.