THE STi is only available with Subaru's new six-speed manual transmission, which has a close ratio gear set and shorter shift mechanism. The transmission is fitted with significantly larger gears - increased gear diameter and thickness - than the WRX's five-speed manual for added strength and durability. Bearing size has also been increased to cope with the engine's higher power output. Double cone synchromesh mechanisms are used on first, third and reverse gears, while second gear features a triple cone synchroniser to deal with the punishment of quick first to second gear changes under hard acceleration. The transmission case is no longer a split half arrangement, instead it is now of a single unit construction.