The GT3 RSR, based on the Type 997, featured the latest version of the classic flat-six engine. In 2009, it underwent subtle revisions, adding more hood vents and optimizing air flow through the fascia and hood.
Despite air-restriction rules limiting the updated M97/81 engine to 455 brake horsepower, the enlarged 4-liter engine was tuned to deliver better torque at a lower RPM range. Further changes were introduced in 2010 which ncluded updated air ducting and outlets on the front body panels, a new rear wing, a lightweight wiring harness, and an optimized brake system.
This particular 2010 Porsche 911 GT3 RSR is reported to be one of two models built that year with a 4.0- liter M97/81 flat-six engine, initially delivered to Team Falken Tire for the American Le Mans Series.
Source: Bring A Trailer
