Ok, I have the new bits, Chain, and all guides. Didn't elect to do the tensioner since I NEVER read where one went bad and it is DEAR cost wise. Questions are, does everything come out easily or do I need to know something special, AND what about timing marks? I read what I found in the manual and saw nothing about timing marks.

oops ....yes they do bugger up

better do some more searching through the forum ,...mostly from blocked oil paths and gunk under sharks teeth gears at the bottom of the piston

timing marks are simplicity itself ....look at the cam gears and crank dowel .... you may have to rotate 1 crank revolution to see it properly at tdc on cylinder 1

read the factory - bmw workshop manual ...its all there .,, and available off the forum downloads section for free ....print it out ..it is invaluable

good luck with the work ....take pictures ...and read up on what youre trying to do.... before you start...its all here in the forum ...

Make sure you get the right chain. Some reported having been provided with chains that had two extra links.....

I just did mine. Result was that the chain was not all that stretched but the tensioner guide (bottom) and side guide were badly worn. The rattly noise she made when hot disappeared after the operation.
The tensioning device itself should not need replacing. Just the plastic guides and the chain.
Here are some things to watch out for.

• As charlie points out, really good idea to read up on the procedure before hand. Do not attempt this until you have a clear idea about what you need to do. Worst case scenario would be your camshafts could move out of time with the crankshaft.
  
• You need to remove both crank and valve covers as well as the timing chain cover so best to replace the rubber seals for those while you'r at it. Timing chain cover has no gasket/seal so use an RTV like permatex.
  
• When removing the timing chain cover just loosen all the 6mm socket head bolts ¼turn first before undoing completely otherwise the last one could bind and possibly strip the head.
  
• Check the tensioner mechanism to make sure the inlet and outlet oil holes are not blocked. This has been found to be a problem but mine were ok. When I took mine out and squeezed it together oil squirted out both holes. The inlet is at the back where it bolts against the front of the sump. The outlet is under the guide rail at the top.
  
• You must ensure that #1 cylinder is at TDC on compression stroke before removing the chain. This ensures there is no pressure on the camshaft lobes which may turn the shaft when the chain is released thereby messing up the valve timing. Workshop manual describes the process. There is a timing mark on the casing and drive sprocket. If your manual doesn't mention timing marks I'd be checking with another book.
  
• You may want to order a crankcase seal which doesn't come in the timing chain kit.
  
• Refer to a workshop manual for torque settings and a complete description.
  

Links:

• http://www.k100-forum.com/t10758-rattly-timing-chain
  
• Timing Chain Rattle Diagnosis and Repair
  
• Motorworks Cam Chain Kit
  

Tools Required:

• Spark plug spanner
  
• Metric socket set
  
• Open-ended spanner
  
• 3/8" socket head driver set
  
• 3/8" Torx driver set
  
• Tension wrench with ½ to 3/8 adaptor