Soon I will be installing a dubro vibration reducing mount on a 90 sized plane with a cowl. Being that the entire purpose of the mount is to absorb shock I assume that it will flex a little bit as the engine runs. HOw much movement can I expect and do I need to cut the cowl any different around the carb and prop to all ow for side to side movement?

What about forward and backward movement? Will I need a little extra gap between the spinner and cowl to allow for slight compression of the mount?