Well i recently sold my decat pipe and reverted to the cat. Reasons? I had upgraded from 180bhp Duratec to 210 cams and the car started to fail the brands hatch drive bu noise tests, secondly, got fed up with the increased noise during normal driving, just too loud, im getting old and don't want to damage my hearing. Also had to refit the cat for the MOT so decided to declutter and get rid (sold £150). Havent noticed any changes in performance but the exhaust noise is less harsh and a little more room in my shed :-)