if you drop a 4.7v zener diode over 2 (of the 3) wires of the MAP sensor in the boost pipework, this will clip what the ECU reads to about 17psi.

Sorry for dragging up an old thread lads but i need to know which two wires the diode goes across for the Ibiza. All the how to's online have different coloured wires:headhurt:

Don't worry lads I've got a wideband, EGT and vag-com so i can keep an eye on things but i'm planning to get the car mapped to suit but this will tide me over until then.