HKS is reportedly developing the GT4955 sports turbocharger kit. It retains a housing the same size as the GTIII-RS while targeting higher output with newly designed blades. Vehicle-specific kits, including one for the GR86, are also planned for the GT4955.
Continuing its long history of turbo tuning, HKS has outlined a policy of combining the GTIII series with its new-generation ball-bearing turbochargers and selecting the optimal package for each application. Legendary products such as the GT3037 and GT2530 remain well known, and the GT series has addressed the needs of individual vehicle models through comprehensive development, including ECU control. The GT4955 is positioned as a next-generation product.
The GT4955 retains the same housing size as the GTIII-RS while using a larger-diameter compressor wheel. Whereas the GTIII-RS uses half-blades, the GT4955 uses full blades with pointed tips and increases the outer diameter by 8.8 mm to secure the required airflow. The wheel is machined from billet to make it thinner and lighter, while the proven floating-metal bearing design is used to achieve both responsiveness and high airflow.
The exhaust side also has the same outer diameter as the GTIII-RS, but uses a revised blade shape. Its more streamlined design expels exhaust more efficiently and is intended to extend power into the high-rpm range while maintaining responsiveness. The target output range is from the 300-ps class to approximately 600 ps. It is also suitable for use with large-displacement engines such as the RB26.
Development is progressing toward launching the universal version and the GR86 sports turbocharger kit by the end of 2026. Vehicle-specific development is also under way for the Stage 2 model of the ZC33S Swift Sport and for the GR Yaris and GR Corolla, while additional functions such as direct-replacement turbochargers and the Flash Editor are also being considered.