I have the Mazda Comp engine and trans mounts. Can't easily tell the difference from stock. There are no objectionable vibrations under any conditions or RPM. Many modern "sporty" cars have drivetrains this stiff from the factory.

 

I used to break Mzda Comp front diff mounts at the strip left and right, even with a pinion snubber.

Probably just fine for street use.