I changed this the other day on mine, it took me a bit more than an hour. My DV was held on with three T30 bolts. I didn't bother taking off the engine undertray, and the main issue was that there was limited space around it, so I had to move the bolts about 10 degrees a time, whilst lying on my back with one arm through the wheel arch and the other straight up.
It made a big difference to my car though.