This is the Tuned Pipe System for the OS Max 61 SF Series Engine. FEATURES: Pre-Tuned to operate on the OS .61 SF engine Lightweight Aluminum Construction INCLUDES: One Tuned Pipe One 90 degree header One Tuned Pipe coupler Two 6" tie straps for coupling Two Header bolts to attach the Header to the engine COMMENTS: This is a Complete Tuned Pipe System. For Tuned Pipe Mounting Kit, order MACG9231 NOTES: Exhaust port: rectangular 9mm x 29.5 mm Exhaust mounting dimensions: 43.8mm between center-to-center JAK 10/26/98 ir/jl