The exhaust system on our car looks pretty much new so we will try and reuse this. The mid and rear boxes were unbolted as one unit from the cat. Next the cat was removed and then the front pipe from the manifold (firstly disconnecting the lambda sensor and marking up the loom). The front pipe to manifold bolts were a pain to get to whilst lying under the car with multiple extension bars on the ratchet (wish it was over the pit in my garage!). Plenty of WD40 and some grazed knuckles later and the nuts came free.