Rich, are you saying 1 of your mounts is 1/4" taller than the other or both? Its of no surprise to see the rubber tab fail on any SC given the age of these cars in addition to the heat cycling. That tab was put there for a reason, to avoid metal to metal contact (a point discussed earlier in this thread regarding the knock sensor) and to lesson the vibrations transmitted to the cabin of the car for comfort purposes. Removing this tab to install a taller mount is the precise direction people should not be going in. Remember, your system is as strong as its weakest link....remove the tab and see how long metal vs metal last as they wear against each other in addition to the points mentioned above.
You seem very confident in your product which every vendor needs to be, so I ask what your warranty and return policy is with the mounts you offer. Ill gladly give them a try in my SC but first want to know if, rather when, I tear them apart without the use of a limiting tab or torque strap, what kind of compensation will you offer? Understand, this post is in no way an attempt to begin a war, rather, to cure a more and more common problem SC owners are experiencing as they begin to modify their vehicles further and/or drive them over time.
Putting aside the issue of the arm being higher since the MN12Performance mounts are higher, how do you address the passenger side bracket having about an inch of room below it to slam as it bottoms out since the motor cant raise up on the drivers side? My point here is a solution needs to be provided which address the problem at hand, the overall movement of the engine when under heavy accelleration. This requires addressing both motor mount brackets and the limiting tab.
Paul