IE's downpipe includes a high-flow 200 CPSI catalytic converter. This performance CAT allows for full and unrestricted power from Stage 2 ECU tunes and hybrid turbo upgrades while reducing emissions output and eliminating unwanted smells and bumper stains found on cat-less designs.

The stock downpipe becomes a significant restriction when upgrading to a larger hybrid turbo. IE's cast downpipe is a direct-fit to available upgraded turbochargers on the market and will allow total horsepower, torque, and spool potential from your turbocharger investment.
IE's B9/B9.5 S4 & S5 intake system, turbo inlet pipe, and downpipe are hybrid optimized, making the installation of popular turbo upgrades an easy bolt-in process.
Real-world power numbers are achieved using our in-house dyno cells to verify the efficiency of the downpipe design. Dyno testing performed in controlled conditions on a hybrid turbo equipped B9 S4 resulted in consistent and significant power gains of 45HP & 41FT-LBS to the wheels!
The following chart details the power gains (WHP & WTQ) over the baseline power numbers taken from the stock downpipe on our hybrid turbo development S4. The "0" baseline is the maximum power/torque made, and each following increment is the additional power gained from the IE downpipe upgrade.
The above power gains are a result of various design details:
The 6" 200 CPSI racing CAT improves exhaust flow.
The increased size of the downpipe body and smooth transition into the midpipes quickly evacuates exhaust gases away from the turbine wheel, improving turbocharger speed and efficiency.
The thick-wall investment cast body reduces radiant heat keeping the engine bay and charge air cooler.
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