Subaru has unveiled its awesome new Subaru STI Performance Concept at the New York Auto Show, and here are some great pictures. The Subaru STI Performance Concept has an engine based on that of the Subaru BRZ Super GT racing car. STI (Subaru Tecnica International) is Subaru’s performance arm, and signals the start of the firm introducing STI-tuned cars in the US — great news for Subaru fans. Subaru STI vehicles offer improved suspension, brakes, chassis, aerodynamics and performance. And it would be no bad thing if the STI Performance Concept is anything to go by.