Used this DIY to get my local mechanic to change the downpipes and he did it step by step in about 2 hours. Cost = $200 :P. There were a couple of hangups due to us missing a step and having to undo some things and getting the clamps on the turbo pipe was a bit of a hassle but everything worked out. I can easily do it again now if I have to go through warranty work.
Current: 1987 E30 325is, 1997 E36 M3, 2004 E46 M3, 2015 F80 M3
Past: 2011 E92 M3, 2011 E92 335is, 2008 E90 M3, 2007 E92 335i, 1995 E36 M3