hi. im also inerested in gutting out the cats. i drove few 325i similar year non-vanos and my 325i has different noise than the others. then u push accelerator it sounds more like a plane than a car , and i havent noticed any damage on exhaust and its all stock. MOT went well. so im wondering if it might do something with cats? acceleration of my car also isnt as good as others i tried (engine is good arround 12 compression ratio). i didnt change stock air filter either since i bought it, might it be the case?