LOOK AT THE OTHERS SPECS- THEY WILL BE MILD STEEL (WHICH RUST) OR 409 STAINLESS. THE CHEAP OF THE CHEAP. OURS ARE 321 SUS AUSTRALIAN. Shorty design for power gain from idle to mid-range RPM. OE style ball socket collector connects to factory exhaust head pipe. Fully mandrel bent tubes made of 16-gauge 321 stainless steel. Head flanges laser-cut from 7/16-inch thick steel plates. Flanges flattened by hydraulic press for precise and leak-free seal. All joints TIG welded for resistance against cracking and wearing. Polished surface for extra protection against rusting.