Megan Racing engine and transmission mounts are a great upgrade for your Lexus IS 300. Stock engine / motor and transmission mounts are usually designed with very soft rubber and flex quite a bit. In addition, over time the soft rubber can degrade and become even softer or tear.
Worn out engine and transmission mounts can make a vehicle feel "sloppy" and vague. Soft or torn mounts also allow excess engine movement, which can reduce the amount of energy (horsepower) that is able to be transferred to the wheels.
Megan Racing designed these hardened engine and transmission mounts specifically with performance in mind. Using a harder rubber compound but retaining the original design allows these mounts to be a direct bolt in upgrade. As a result of the increased rubber durometer the Megan Racing engine and transmission mounts provide a significant improvement that you can easily feel. Generally you will notice "crisper" response and much more feedback from your engine and transmission, including better acceleration, deceleration and shifter feeling.
As with all performance engine mounts and inserts, you should also expect to feel a few more vibrations enter the passenger cabin. These vibrations can actually allow you to be more "in tune" with what your engine is doing and how it is performing. As a result you can expect to feel more connected overall to your Lexus IS 300.