We recently completed a GiroDisc Install on a customer's 996 TT:

These rotors offer many advantages:
-Lightweight (2lbs per corner less than OEM)
-Size (350mm Vs 330mm (oem))
-Materials (high carbon content iron)
-2 piece design

Which results in the ability to shave seconds off lap times and mitigate brake fading/glazing on track.
Front:

Rear:

(ignore the weird wear marks, we hadn't bed them in yet)

The only issue that you can run into with these rotors is that due to their larger size they won't fit under your aftermarket wheels.
Giro Disc claims these will fit under most OE wheels, however they didn't fit under the customer's RH Turbo P wheels.

To remedy this we installed 15mm H&R spacers on all four corners (they did, however fit under his 18" OZ track wheels sans spacers)





These spacers gave a nice wide stance to the 996 on it's street wheels.

Check out the Rotors and Spacers or many other Porsche Parts on our Website