Black Mamba 4.5" (114.3 mm) > 3" (76 mm) Decat Downpipes for Audi RS4 B9 and RS5 F5 2.9 TFSI, expertly crafted from T304 stainless steel for maximum durability and performance. This 2-piece kit eliminates the factory catalysts, delivering a significant power gain of up to 34hp on Stage 1 setups, whi..