Hi Gorp, this is a very good question - thank you for seeking clarification on this point...
So, there are two main variants of the curved lane changer mod as introduced within this thread. The first requires two 10mm dead spots to be formed, side-by-side, at some point in the changing lane section of the track piece (please see blagard-01’s first set of photos on this thread). This ‘side-by-side‘ approach will work with all types of lane changers regardless of whether the exit flipper/wedge is ‘floating‘ type (pre circa 2005 production) or the later ‘fixed‘ type.
If the exit wedge is of the later ‘fixed‘ type (i.e. locked firmly in a centred and fixed position usind a small locking pin on the underside) then the simplified ‘single-sided’ variant can used as per the later more recent photos shared in this Thread. These later photos clearly show the correct positioning of 10mm single dead spot and, as you will see, blagard-01’s photos are almost identical to mine in this regard.
I hope this explanation is helpful :-)
This leaves one further question... if using the ‘side-by-side‘ variant - where is it best to location for the dead spots?