This covers all of those abbreaviations used in megasquirt talk. TPS, MAP, and all that stuff!
Megasquirt is a Do-it-yourself Engine Management computer.
This article covers what megasquirt is in general terms.
Why relay your headlights? What is a relay even? All of your questions are answered right here! Relays make your headlights brighter by directly connecting them to the battery with a sort of remote switch called a Relay. It is a required modification for Scirocco II with European lights, the wires are different, and the wattages are higher.
US headlights on a lot of our cars have very low wattage, sometimes as low as 35watts. European headlights with H4 bulbs start out at 55 watts and can go above 120 watts per bulb. Stock wiring cannot handle this extra load. The way the headlight system works in a VW is for the power to go from the Battery to the fuse panel, through the load reduction relay, then up to the headlight switch, then all the way back out to the headlights.
A headlight relays system acts as a remotely controlled switch. Now the power runs from the battery to the relay to the headlight – a very short distance. The relay is told to turn on by the stock wiring. A relay uses far less current than the headlights do, taking a load off of your electrical system, and making your switch last longer.