APR's S4 Cat and Downpipe Exhaust
replaces the the exhaust from the turbochargers to behind the lower
factory catalytic converters. The system removes the factory pre-cats
right off of the turbocharger and includes six separate components.
Included are the two pipes off of each turbocharger, a set of pipes
with catalytic converters, and a set of test pipes without cats. With
TIG welding, fully stainless construction, and CNC'ed hangers, you will
not find a higher quality system on the market.