Replacement factory Mazda "donut" style gasket for the junction between midpipe and muffler on the 2016+ MX5. These live a hard life on theMX5 ND as Mazda made it a flex joint with one flat side and one rounded side and springs in the connection so that as the muffler moves around on the rubber hangers it grinds against the gasket and is held there by just spring tension. Over time all that grinding slowly wears away the gasket and it gets thinner and less effective.

If you have a leak at this junction when you change to an aftermarket muffler, likely this gasket is just too worn away from sporty driving fun. Changing to a fresh gasket as sold here usually solves the leak.

Note this will not stop condensation weep at this joint. It's a moving joint, metal on one side, condensation passing through that sort of flex joint is going to happen and we see it on these cars brand new from the dealership. But if you feel 'puff puff puff' actual exhaust gases leaking then consider a replacement. Another trick is to increase spring tension with a few washers between nuts and the springs to 'push' the gasket a little harder into the mouth of the muffler side receiver.