aFe 49-34140 Gemini XV 4 IN to Dual 3 IN 304 Stainless Steel Cat-Back Exhaust System w/ Cut-OutaFe 49 34140 Gemini XV 4 IN to Dual 3 IN 304 Stainless Steel Cat Back Exhaust System w Cut Out Performance Gains: This system produced gains of up to +11 HP and +13 lbs. x Ft. TQ., as measured on aFe Powers in house dyno. 4" to Dual 3" 304 Stainless Steel Tubing: This system is constructed of durable mandrel bent 4" to dual 3" 304 stainless steel tubing for maximum corrosion resistance. Mandrel bent tubing for maximum air flow and low turbulence;