Hi guys, just treated myself to an ep3 (the dc2 was getting abit old)
i have just purchased a new exhaust manifold and decat but i read this will give me a cel light?
How does the ecu read the cat is removed? how can i sort this (resistor?) and does anyone know is it just a cel light or a limp mode?

 

Has a sensor after the cat to monitor the cat. Build a voltage divider(2 resistors in series) to obtain optimal O2 voltage and 'trick' the ECM into thinking it's there. I know for a FACT this works on P28's. Don't know about the K series ECM's. The math for the resistors is easy, and I can't give you specific details because I don't know squat about the ECM for your rig(plus it's kinda illegal depending on where you live).