not maf, MAP sensor, its the sensor that is on the oem cupra intercooler, its a diode mod, like a resistor but only lets powere go one way and "caps" it, when ya map sensor hits it "safe" limit it will send a 5w signal to the ecu that put the car in to limp, if you cap the max it can send to 4.8w for example it cant put you in limp BUT be warned, just as the car isnt seeing the boost "propperly" does mean to much boost and boom, mine was spiking 18psi and would hold 15psi and was fine, never had any dramas. and that was running about 230bhp ish
will find a link, (not sure if i did a how 2 or not)