Excellent street, strip, oval track, truck or marine performance upgrade. Maximum torque and throttle response from idle to 6,000 RPM. Best for 327-400 cubic inch engines. Works with most standard components. Dart’s SHP (Special High Performance) 23° 180cc cylinder heads provide an affordable option to those looking for the weight savings of an Aluminum head for a street performance engine. The SHP is designed to work with most off the shelf components. The SHP head’s precision cast ports are designed to offer excellent flow and power without the need for CNC porting. Optimized chambers increase combustion efficiency, and multi-angle intake seats and radiused exhaust seats dramatically increase performance. Manganese Bronze valve guides increase the life of the head.