2009-11. 3.0 LITER. Resonator w/pipe lock nut. A solid metal or plastic block with a threaded hole in the center which is used to tighten or adjust the Exhaust System Resonator. A spring bolt, which is a specially designed shouldered bolt with matching spring and Nut. It is designed to bottom out against the flange, which preserves the spring's force (acting as a locking measure) without over-compressing it, which can lead to failures during the high temperature cycles found in Exhaust. These bolts always mount through the flange, with a Nut on the backside. Exhaust Flange Nut. Exhaust Pipe Nut. Bolt and Spring. Flange. w/Pipe lock.