Kit Number 05186NOS is intended for use on the 2.0L 2 valve “split-port” & 4 valve “Zetec” Ford Focus. Jetting information is included for increases of 35 and 50 HP at the flywheel. This kit is designed for vehicles that are completely stock or have minor changes such as an air filter, headers, exhaust, and athrottle body change. It is not designed for engines with major changes, such as heavily-ported cylinder heads and camshafts.It is designed for vehicles with stock injector and fuel pump combinations. The stock spark plugs need to be changed to acolder plug. See Chapter 3 for spark plug information. Kit Number 05186NOS flows all fuel through the stock Ford injectors. Proper fuel flow is accomplished by altering fuel injectortiming and pressure. Do not use with larger than stock injectors. Driveability, fuel economy, and exhaust emission should not be affected under normal (part throttle) vehicle operation.