I cannot see why adding a late double disc (Field fix) should improve an earlier clutch by removing one fiber and metal disc.
The total package will be thinner and less friction.
I tested this last summer.
- Removed 1 stock metal disc + 1 fiber. Put the later double disc in the middle.
This did not make the clutch more silent at idle.
I even replaced the clutch cover, it had a later.
I rebuilt stock setup with new fibers since I had a new Cruzinimage clutch on the shelf. Old fibers not that much used, also Cruzinimage clutch.
Stop screw opened 1/4 turn from closed a must to reduce rattle at idle (If stop screw has been opened more)
A few photos.
The caliper measurement photos have parallax issues (from side) and not showing exact.
My modified K6 got a complete later clutch with double metal disc + 5 std metal discs and 7 fibers. The outer steel basket deeper and the clutch alu hub also deeper for the thicker package.
This is more rigid and better for more power, like 2 clutch packages with the double metal in the middle.
Harder springs too.