PFF76-923 Upper Gearbox Mount Insert is an affordable and easy-to-fit bush insert made from our Yellow 70A Durometer vibration-absorbing material, which works to stiffen the OEM upper gearbox mounting. This reduces twist of the engine under acceleration and during gear changes, giving the pedals a more direct feel, as well as reducing wheel-hop and letting you get the power down that little bit quicker. We recommend fitting PFF76-923 alongside our other Yaris GR powertrain inserts (PFF76-920 & PFF76-925), as they perform much more effectively as a full set. There will be a minor increase in NVH when stiffening the powertrain mountings. PFF76-923 is made from our Yellow 70A material and works bystiffening the OEM powertrain mounts reducing the amount of engine/trans roll and movement during hard acceleration and gear changing for a more responsive feel.