Today I just finished installing the turbos on my 2001 Audi S4. I just wanted to go over the basics for those who are interested. I will also leave a list of torque values below for your convenience. To begin, you must purchase new turbo installation hardware. This includes all necessary gaskets and crush washers. If you fail to do this, you have a high chance of having a leak. Honestly the process was fairly simple and took me around 1-3 hours total for both turbos. This also my first time doing this, so there was a steep learning curve. I will attach a link to the video that provided the best insight to my installation. He mentions that shaving your wrenches using a belt sander makes installation easier, but I was able to use regular wrenches for install. Just make sure to take your time and try not to stress over the little things. Best of luck with installing your new turbos!
(1) Oil feed line nut - 15 Nm (11.1 ft-lb)
(2) Oil return line bolt - 10 Nm (7.4 ft-lb)
(3) Turbo to header - 25 Nm (18.4 ft-lb)
(4) Banjo bolt - Tight enough to crush NEW copper washers