APR has a stainless steel, mandrel
bent, cat-back exhaust for the S4.
APR's S4 Exhaust is a stainless steel,
mandrel bent, cat-back exhaust. Our exhaust begins after the two lower
factory catalytic converters and is two 2.25" pipes that merge into one
3" pipe. This exhaust is very quiet and simply changes the tone of the
exhaust to a deep, unobtrusive sound. With TIG welding, fully stainless
construction, and CNC'ed hangers, you will not find a higher quality
system on the market.
APR's S4 cat-back exhaust is available
with two different sound levels. The Stealth exhaust helps to maintain
the S4's subdued character. While louder than stock, it is not too loud
to attract attention. The SRT exhaust replaces the center muffler with
a special side resonator. This exhaust has a more aggressive sound and
a distinctive note.