Hi Viper. I had sports cats on mine and removed them a few years ago because the nuts were nearly rusted through and gave them a coat of zinc oxide paint. The boy in me couldnt resist staring the engine it sounded bonkers quite frankly and the ecu light came on immediately. After re assembly and the cats fitted the light stayed on and the car started revving on its own not hunting but revving, switched off started again the revving stopped but the light stayed on. Someone might have been the factory told me to dissconnect the battery leave it for a while then touch the battery with the positive terminal a few times and to my amazement the light went out .Back on topic I think you might have issues if you remove the cats but in fairness my exhaust system wasn't connected up when i started the engine. Stupid question have you got a sports exhaust fitted some people think if you have a quad exhaust its a sports exhaust this is not the case on an Aero.
