Our solid lifter cams are perfect for restricted engine sizes of 32-40mm with a 48-58mm turbo and will provide excellent throttle response specifically for GPA rally 4G63 engines. It is important to note that these cams cannot be paired with OEM hydraulic lifters, and a solid lifter conversion is required for use. We suggest using valve spring KVS63-BTK for optimal performance while running at maximums of 8000rpm and 35psi boost.