My car S with some mods -see below-. My friends non S totally stock.
S with mods, 2004, 55,000 mls.
Non S, stock, 2003, 33,000 mls
-Brakes, about the same. I need to change my brake fluid ASAP! My pedal felt softer compared to my friends car, fresh fluid makes a difference!
- Shifter, I have the "standard" 997, his is stock, BIG difference! Long throws to much shorter. Sloppy to snappy.

effort about the same.
- clutch, mine felt a bit stiffer. Pick up point about the same.
- Shocks/springs, we both have the stock setup. Mine felt def older, time to rebuilt/service.
- Wheels, I have the 17" , his 18" and that makes a difference. I prefer the 17" setup since it feels lighter and less harsh. With the spacers I use turn in is same. I still am convinced that the strut brace makes a difference as well, just feels sharper.
-General, it's only me but I like the black cluster better than the white background in the S. Also, my friends car had no door sill plates? Other than that everything else seems to be equal.
-Engine, well, huge difference. When driving back to back it is very obvious that mine is just simply so much more powerful in every respect. And with that said the non S is still a very fun car to drive! But having a choice when looking for a car go for an S, no question! My friend who drove my car came back with a big grin on his face.... And said "what a difference"
Oh, and both cars had the 3,200 rpm vibration......2nd gear slowing down.
So there, a lot we knew already but for me it was fun and informative to compare.
Later,
Andy