Frontpipe to manifold and MIddle section to catalyst nut. This is M12 x 1.25mm with a 17mm Hex which is quite rare. This size hex allows you to use a normal socket on the front pipe to manifold studs making fitting the frontpipe a whole lot easier. A lot of aftermarket suppliers supply normal nuts which are not designed for the high temperatures encountered. V6 FTO's use 4 of these on the frontpipe to exhaust manifold & 2 of these on catalyst to middle section of the exhaust. 1.8 FTO's use 2 of these on the frontpipe to exhaust manifold & 2 of these on catalyst to middle section of the exhaust. For Exploded Diagram of these locations See HERE Price is for ONE Mitsubishi Part Number MB059359
