Mark - I found this reference point on an older (but excellent) threads;
When I last spoke with Mark at Eurotek (sill plate reinforcement pieces), he provided me this information :
- Prior to 74, chassis metal is .032", thereafter, .035" (20 gauge)
- RSR used two layers of .070" on the sill plate.
- On the longitudinal pieces, .035" before '85
- After '85 (C2 and C4), went to .080" thickness
Sorry. I forgot who provided the following info., but thanks:
Restoration Design replacement panels:
Inner rockers, 0.059" or 16 gauge
Outer rocker sill, 0.046" or 18 gauge
Link:
http://forums.pelicanparts.com/porsche-911-technical-forum/324403-added-sheet-metal-later-coupe-bodies.html
That suggests that even a 18 gauge panel (1.214mm) would make a difference, as that combined with the original 20 gauge (.912mm) would be roughly equivalent to a 13 gauge (round up from 2.216mm combined thickness) panel. That would make it slightly thicker than post 1985 cars.
So the question becomes how much improvement is a worthwhile improvement.