The exhaust system is a welded fabrication that matches the exhaust port on the Power Bee block quite well. It was fastened with 2 5/16-18 UNC hex head bolts with 1/2″ hexes. The top one was easy to get to but the bottom one is a project requiring quarter turns with an open end wrench. I have been trying to use the original hardware wherever I can but this manifold needs my A1237 stud kit big time. The stud kit reduces the chances of cross threading and or stripping the engine block threads. The 3/8″ hex jetnut (rated for Mach 2) allows using a box end wrench in this tight location. The jetnuts are self locking but I like to run a tap through them because I am old and have no patience.