Remove upper air filter box with MAFs and intake tube on Bank1.
Remove lower airfilter box,one screw(10mm socket) and the clamp for the tube of the intake funnel under the headlight.Push airbox towards engine to get it out.
Under the Vanos unit above the A/C compressor the screw for the tensioner is located(don't remember if it was 19mm or 21 mm socket,but you will see on the screw of the new tensioner which size it is).
A mirror is quite handy to get the socket on the screw head,otherwise feeling it with the hands works also well.
Put a towel or something like that on the A/C unit,a bit oil comes out when the tensioner is removed.
Bolt in the new tensioner and tighten it down with 50NM.
Assemble the air filter box again.
There will be a bit rattle from the chain for about 30 seconds until the tensioner is filled with oil.
Check for leaks and get yourself a beer
This is how the tensioner looks in all its glory,the aluminium crusher has to be ordered seperately.