Sorry Rdane- wrong choice of words with period correct. I should have said non factory !
There were quite a few mods done by club racers during the 911's reign on the tracks. Some were just massaged for more clearance, some crude "can opener" style, and others well finished as r dane's blue bomber is. And of course the fiberglass route.
(AIR was probably the largest contributor to the body conversions in the Porsche community. )
The 1974 911 that came with flares from the factory was the RS 3.0 and Iroc RSR. (The actual RSR came with fiberglass flares bonded to steel fenders and quarter panels- a very time consuming process, but the rules stated (loosely translated) that the flare was to be an extension of the standard fender (the RS 3.0)
The RS 3.0 / Iroc RSR has steel fenders with hand welded flares (lap welded too i might add) that were hammer dollied to be pretty smooth. The fronts and rears were very much the same as the 73 RSR. With the exception that the fronts were shorter on the leading edges to accomodate the G series (short hood) styling change.
When compared to a turbo flare, these are fairly crude looking with an elongated opening and a folded edge. Each car varies slightly due to its hand assembled nature. The width is comparable to the 75-94 turbo , commonly known as 9 and 11 inch flares
When looking to replicate a RS 3.0/ IROC RSR, one should consider the extra work needed to massage turbo steel flares into the correct shape. It could make a difference to you.
To others, not such a bid deal to go to the expense capturing this detail.
This car posted here has standard turbo flares
