@Dean0 I'm about to put progressive springs in my Roadster and was also wondering the same thing. The Progressive springs will have more volume causing the resulting air space to be reduced if using the standard amount of oil. What did you find out?
@BillB mentions this in a post here about an R3T (
Touring progressive fork spring upgrade)
"Book says air gap of 110mm. Instructions from Progressive sez nay. They say 140mm is absolute minimum air gap due to the spring design displacing more oil. I tend to think that the spring instructions over rule the manual in this case."
The 30mm difference is about an inch, which seems pretty significant.
I can't find anything on the Progressive site about this. Maybe it will be included with the springs when they come? If not, wondering if it's a different spec for the Roadster.