I just installed the JCW injectors on my MCS and it was super easy. All I did was take off the gas cap (to release pressure from the system) and then take off the intercooler and unbolt the fuel rail. I hung the fuel rail into an oil drain pan and pressed down the release valve on the end of the rail to release the pressue from the rail (the release valve looks just like the air filler tube on a car/bike tire with a twist off cover on it). A small amout of fuel suirted out under pressure and into the oil drain pan. After that, I simply unclipped the stock injectors and installed the new ones (I coated the O-rings of the new injectors with a small amount of anti-sieze lube that I bought from the local auto parts store - found in a tube for about $2). I then re-assembled the car, turned on/off the ignition a couple of times (without starting the car) and left it in the number two position (where you can hear the fuel pump running) for about 5-10 seconds (to prime the system with fuel), and then I started the car. It fired right up the very first try without a problem. I then inspected every thing for leaks, etc.

Very easy!