I see.
I'm keen to see whether they'll be more popular on the GT3 CLASS. As you don't see many 911s these days.
The problem is the two classes which are GT3 and GTE. The 911 GT3 R races under the GT3 class and the 911 RSR races under the LM GTE class. Each of the classes have a differing rule set as that's where it can get a little confusing.
I do wonder if the 2017 RSR runs a 4.0 engine with two blowers on it, so it brings it in to line with the completion like Ferrari.
GTE
Currently the top division of GT racing, this was formerly the GT2 class, and has now been renamed to ‘GT Endurance’ and split into two categories. GTE-Pro caters for brand new cars with professional drivers, and is often replete with factory teams, while GTE-Am caters for teams running a car that’s at least a year old, and with at least one Platinum or Gold level amateur driver. The cars are identical between the two classes, this time based on production models and required to share the same overall external dimensions as the cars on which they’re based. 5.5-litre naturally-aspirated engines and 4.0-litre turbos are the maximum allowed, with no limit on cylinder capacity. Steel brakes of any diameter are permitted, and weight must be 1,245kg or more. GTE cars are able to participate in the European Le Mans Series (ELMS), the World Endurance Championship (WEC), the Nurburgring Endurance Championship (VLN) and the American Le Mans Series (ALMS).
GT3
GT3 cars are more production-based than any of the above classes. Unlike GTE, GT3 doesn’t have a specific set of technical regulations, but each model is assessed and homologated individually, and it’s at this point that the amount of restriction that should be placed upon each is decided. However, on the whole, regulations are stricter than in GTE and preclude too many exotic modifications to engine and bodywork; performance is balanced between cars with the use of restrictors and ballast. GT3 cars are eligible for competition in the FIA GT Series, the Blancpain Endurance Series, the VLN, the Grand-Am series, and the British GT championship, among others.