Extractors
Extractors are expensice beacasue of certain material used and coating, each brand has there own technology like bend,and etc...
Got this off Pacemakers website:
For over a quarter of a century, Pacemaker has been innovating, designing and manufacturing quality exhaust headers in Australia. Pacemaker was the first company to introduce mandrel-bending technology into the exhaust header market, forever changing the header industry landscape.
Today Pacemaker still draws upon its long tradition of innovation by introducing new technologies into the market place. In this time Pacemaker has been able to design and build one of Australia's largest 4-into-1 and Tri-y catalogues. In 1997 Pacemaker introduced its turbulence eliminating 'pipe over cone' technology (design copyright number 135712). This advance in design and construction not only dramatically improves flow through the exhaust but also helps to lengthen the life of the product.
Even more recently Pacemaker has introduced a shot peen process over its entire range. This process, while used to remove scale oil and other debris from the product prior to painting, has an interesting side effect. During a shot peen blast, the surface area is expanded and fine cracks and sharp edges are smoothed over. This also helps to extend the life of the product even further. This method of shot peening is also used in the aviation industry as well as in the building of high performance engines.
Hope that gave u some understanding.