Glue should be used at all joints to fill any spaces. Any spaces will degrade the performance of best subwoofer for music only your subs, not to mention the annoying noise air makes when being pushed out of a small hole. On applying the glue, let it cure for at least 24 hours before mounting the subs. This is a precautionary measure to protect the rubbers used to make the subs from the high fumes that some manufacturers glue products have.
