'Question : Did you break a hole through that wall to find out thats where a staircase closet is at or there was already a storage area there before?"

We broke the hole in the wall.

We have also thought about an air filter and left ourselves open to add easily if need be. I appreciate the reminder. There is 1' of space between the floor of the room and ceiling of the garage which would be perfect to hide the filter and or muffler.