This is the kit that professional or advanced amateur engine builders will want for bigger than stock engines. There are no nylock nuts in this kit! We have taken out the basic copper exhaust nuts and included our 11mm socket size exhaust nuts for bigger header diameter clearance. Also included are our exclusive case half nuts with original VW 17mm socket size. These will clear most big bore cylinders without modification. This kit if for those with 10mm head studs. Most items are zinc plated for a professional look. Try one of these premium kits!