I like this thread.
About a year or so ago I bought new rotors and pads, because I was convinced my rotors were warped. Bad internet deal so returned everything and got my money back.
Long story short I left my brakes stock. And guess what? Rotors aren't warped. But you get lots of buildup from the pads on the rotors (soft rotors, hard pads). Vibration is there in summer, gone in winter. I have found you can get rid of the vibration with some threshold braking (it clears the rotors of built up pad material).
So with unmodded brakes, and 33K I went driving at 10/10s a week ago down a tight, twisty road. No fade. Totally linear modulation. Grip to threshold with ABS never engaging. Never a lockup. No change to steering sensitivity. I do run Goodyear Eagle F1 GS-D3s, which help enormously.
Though I too was once convinced this car needed modded brakes, I now say NO WAY. SVT brakes outperformed my 914-6 on same road, and it has same size brakes and only weighs 1978 pounds. And on other cars I have run Baers, Wilwood, and Brembo. I love the ability to stop, it keeps me alive.
World class. No need to mod.