Brembo GP4-RX Radial Caliper Kit vs Brembo GP4-RS Caliper

The GP4-RX is the sharper track tool: a CNC-milled two-part body, 32 mm pistons and sinter pads give harder bite and better feel, and it carries TÜV/KBA approval for street use on many models. The GP4-RS is the easier, more forgiving choice: a monobloc body with 30 mm pistons, finned cooling and a lighter claimed weight than the M4, with a softer initial bite. Owners rate both for build quality; the RX rewards aggressive riders, the RS suits riders who want strong road braking without a harsh lever.

• Choose the GP4-RX if you ride hard on track or want maximum bite and lever feel and need a street-approved caliper with pads in the box.
• Choose the GP4-RS if you want a monobloc caliper with gentler modulation, better heat shedding from the fins, and a lighter body.