got to admit when i bought my golf there was a leaking exhaust noise coming from the front, i hoped that it was after the cat but i think it is probably the same problem as yours
keep me posted on the result of your change
an exhaust centre said it wasn't the down pipe but i know damb well the down pipes are a b!tch to change so i'm guessing he was fogging me off because it was first thing on a saturday morning, you probably know the place BOBS TYRES AND EXHAUSTS
so anyway the noise is slowly getting worse and the car is getting slower because of the reduced back pressure with a decrease in fuel econ
maybe i'll see you zipping about stevenage sometime

cheers jay