Originally Posted by Michaelc1220
Ive seen people saying not to replace the motor mounts and to clean some part under the motor but im not exactly sure where.. and the motor mounts should not need to be replaced after 2 months, that would be an incredibly short live span IMO
It wouldn't be that the mount was bad that some of the people want to change at least one of them, but that's the rear motor mount (RMM) or power train roll restrictor. That one allows the engine to tilt under load and absorb some of the slack in the power train, but too much slack leads to a disconnected driving experience. The stock mount is mostly made of rubber there where as the Mazda MazdaSpeed 3 rear mount is much more solid. Although that might nominally increase engine vibration felt in the cabin, it can help tighten up the roll of the power train allowing for less power to be wasted in this fashion. But its not likely to show up on a dynomometer.