What you're feeling is both a craving for a more locked down drivetrain, but also the limitations of your OEM rear motor mount. It's designed to balance comfort and performance, with the intention of being an acceptable mass market result.
HRD Precision Machined Elantra N Lower Motor Mount
HRD Precision Machined Subaru WRX/STi Pitch Stop Mount - Apex Silver
HRD Precision Machined 2012-2015 Honda Civic Si Rear Motor Mount - Apex Silver
HRD Precision Machined 2006-2015 Honda Civic Si Upper Motor Mount - Apex Silver
HRD Precision Machined Subaru WRX/STi Pitch Stop Mount - Midnight Navy
Precision-Machined Rear Brake Wheel Cylinder Compatible with Scion/Toyota