Join Date: Aug 2008
Location: Lowell NC
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Its the stainless "clamshells" around the SRT shorty headers - that metal expands / contracts with temperatures...when you shut down everything starts cooling down.
My 5.7 with its cast iron manifolds would make a loud pop after some time in the garage as things were cooling off.
There's a lot of heat shielding around the exhaust as well as the actual pipes - the cats make similar ticking sounds as they cool down.
You'd be surprised how much an exhaust system "grows" in length as it heats up to operating temperature. When the system is being designed, there's some compensation to allow for the lengthening of the exhaust to insure there's adequate clearance and the hangers are spaced to allow for that...
2016 392 Hemi Scat Pack Shaker 23Y pkg (M6) ordered 8/28/15, born 10/23/15, home 11/20/15
Torred / Black/ Ruby Red leather
2009 R/T 27J pkg (M6) ordered 7/17/08, born 10/23/08, home 11/13/08
Hemi Orange / Dark Slate/Light Slate Gray leather