ok i am just about to change the chain on my 04 450. It had two clicks left when i checked it 10 hours ago. This is a topic i am interested in, but feel cautious of as well, if the chain doesn't have enough tension, and it slips, will the valves hit the top of the piston.
Basically what your saying is before i change the chain i should push the tensioner in with the existing spring, to its current worn position, then cut off what is left outside the housing.I suppose this does make sense as it is the minimum tension required to tension the chain to the right level.
Sparks, is this what you have done, and how many ours has your engine done since you have done this.