VRSF 3.5" E84 X1 35i N55 Stainless Steel Catless Downpipe: Made from hand crafted, Tig Welded 3.5" Stainless Steel. Smooth radius bends to decrease turbulence and increase flow. CNC SS304 Stainless Steel Flanges. Gains from 25-30hp with tune. Gaskets & high quality grade 12 mounting hardware included. VRSF Lifetime Warranty.