I remove the OE downpipes and show how to install piggie pipes, plus a step by step tutorial on the flap mod for the 4.2L V8 intake manifold found on the 2003-2008 Audi S4.

Featured Shop Tools and Project Materials (Amazon)
DEI Under Hood Acoustic Lining: https://geni.us/DEI-underhood-lining
DEI 12"x12" Gold Reflective Barrier: https://geni.us/DEI-reflect-a-gold
Vibrant O2 Sensor Spacer Kit: https://geni.us/vibrant-O2-spacer
Intake Manifold Cleaning Brushes: https://geni.us/bottle-brush-set
Mini Wire Brushes: https://geni.us/mini-wire-brush-set
Centering Punch: https://geni.us/centering-punch
Deburring Tool: https://geni.us/deburring-tool

Skip to chapters
00:00 - Intro
01:07 - Under hood insulation fix
03:46 - Piggy pipe downpipes install
11:27 - How oxygen sensors work
14:34 - Oxygen sensor spacer demo
16:32 - How the intake manifold flap works
26:08 - Flapper mod DIY steps
35:17 - Flapper arm repair mod
35:47 - Goooold!
36:29 - JHM intake elbow coolant bypass