Whether you are rebuilding your six-speed manual Subaru STI transmission or looking to upgrade your gearing, IAG’s 1st-6th Carbon Synchro Set will provide smoother shifting and increased reliability. Aggressive driving and shifting can lead to worn-out or damaged synchros, which in turn, can cause gear grinding or even eventual damage to the transmission housing. The IAG Carbon Synchro Set is an essential upgrade for Subaru drivers looking to replace worn-out synchros and improve the shifting and performance of their STI.

The IAG Carbon Synchro Set features dual carbon friction surfaces, which not only prolong the lifespan of the synchro sleeve and gear teeth but also allow for quicker and more precise shifting. The IAG Synchros are composed of superior Japanese brass, which is known for its high wear resistance, and its ability to be intricately machined. Our Carbon Synchro Set is precision machined for a superior shift feel and for strength.

IAG’s Carbon Synchro Set was designed to provide more surface contact between the gears and the synchros, decreasing gear shift times by increasing grip for quicker engagement. This also improves the driving experience by requiring less force to engage the gear.

The IAG 1st-6th Carbon Synchro Set comes as one complete kit. This Gear Set includes the first, second, third, fourth, fifth, and sixth gear carbon-faced brass synchros. There is no need to source or piece together incomplete synchro sets or hunt for hard-to-find OEM parts; everything you need is contained in the IAG 1st-6th Carbon Synchro Set.