The Audi / VW 1.9L Diesel pistons are made by Diamond Racing USA specifically for ZRP. They are built as tough as can be to withstand the vigorous demands of racing. No matter how much boost pressure you are running or how high you are revving, these pistons will take it and ask for more! Check the individual features for your application below. Product Features and Design 2618 Low-silicon / High expansion alloy for High HP/Boost applications Round skirt design with bottom reinforcing band 3D under crown milling to ensure minimal weight without compromising strength. 3D milling on piston crowns for ready to install finish Over size valve pockets for larger than stock valves and clip cuts on the edge of the pistons Window milling, reduce piston overall weight while maintaining its strength and structural integrity Lateral gas ports for better ring seal Offset pins for quiet operation Total Seal Pro-Select ring set 1.00mm x 1.20mm x 2.00mm Tool Steel H-13 alloy pins (Rockwell hardness around Rc 54) Wall Thick. 6.65mm Diamond Pistons Diamond pistons are engineered with only one thing in mind: Winning races! They are manufactured in the USA from 2618 material. Diamond racing company is known from the late 60s to produce the highest quality engine parts around. The past 2 decades Diamond has solely dedicated itself to manufacturing forged pistons. With all state of the art machinery they offer customers the state of the industry in machining. The Coordinate Measuring Machine (CMM) is one of several sophisticated pieces of measuring and modeling apparatus used in Diamond’s engineering department. The CMM provides very accurate measurements, measuring the location and details of valve pockets, for example, to within a .0001in. This laser scanner is used for modeling purposes, especially for scanning piston domes where it scans thousands of surface points in minutes. Developing the highest quality pistons in the industry by using the latest CNC machinery and computer software aids, as well as providing unmatched quality control. With these credentials it was only a matter of time before we decide that this is the firm to work with for making unlimited horsepower! Optional coatings offered per request. Thermal barrier coating “Blast Off Bronze” Piston side-skirt and under-crown coating Hard Anodized Coating Double diamond coating