I bought an omni power test pipe about 2 weeks ago. I noticed its was 3 piece. Omni's description for it is "Omni Power test pipe are made out of aircraft quality 304 Stainless Steel. They feature an adjustable length & clocking with removable center section. Average 5-10 horsepower increase depending on engine modifications. Omni Power test pipe will work with a 2.5" JDM Header collector and now an available 2.25". Omni Power test pipe bolts up to 60mm exhaust systems" Do i need to weld it?