Hi guys, I'm new to turbo engines and just starting and I've seen/read a lot of Escort RST's with -31 Actuators, what do these actually do to cars performance/running?

Also I've read about adding a 5th injector, anyideas what this would do?

Muchos Appreciated

 

a -31 can run more boost and hold most of it!,

a 5th injector is needed when either no more fuel can be extracted from the injection system, or to provide the fuel from the set level to provide a good on/off fuel economy when driving normal