One of our Users posted new GT3RS information in the german Porsche forum. Only a few short points:
1. power slightly over the original GT3 power...something around 390 HP
2. PCCB
3. weight reduction at least 120 kg
4. street tires (optional: Pirelli PZero Corsa)
5. rear spoiler gets an additional lip, front spoiler gets two little additional air inlets
6. some carbon parts involved in production
7. no A/C, no radio and no Bi-Xenon lamps
8. body the same as on the GT3 (no "wide-body")

Official information should be out soon.

A little comment from my side: I heard that the power stays the same but maybe this info is newer and more precise now.