I have had mine off before, i just removed the back box and that was more than enough. Its not hard to remove the back box, two hangers and one joint. Def get the car as high as possible, becareful with the tank if it has petrol in it. The bolts can be the worst part, time spent at this point might save you oads later. Lots of back and forwards with a T bar and correct socket should do it ok.
Make sure you get the return pipe back on correctly, this can be a real pain as you need to access the top of the tank from inside the car once its nearly back in place.
I found i had to cut the Jubilee clip off the filler neck pipe as it was that old.
A 2nd pair of hand never goes a miss.