I started by removing the side molding, made more challenging by the need to retain the underlying body crease. The 944 has the fender bulges front and rear, the GTS only at the front. I am choosing not to replace the rear quarter panels to correct this and will adjust the add on fender flare accordingly. I created the initial shape from .040" (1 mm) flat stock.
The turbo charged GTS has (4) intake slots between the headlights. It appears these feed fresh air to the inter-cooler. I created these opening with a drill, exacto knife and files.
It’s not appropriate to call this a 924 GTS due to several compromises I had to make with the build. So for my sanity and so I can continue the build I am going to refer to it for what it is: a 944 Turbo Rally. Porsche never created such a car, to the best of my knowledge, so this will be semi-fictitious build.
The horizontal portion of the flare was made with .020" x .250" strips. I glued them in place then trimmed and shaped accordingly. The face was made with .030 flat stock roughly cut and glued to the edge of the strip, then again trimmed and shaped. I did a similar technique on the 914/6 GT.