It's impossible to see a lip or edge between the parent aluminum and the 5.8's cylinder lining. The bore itself, however, looks and feels like iron--because it is. SVT says the Plasma Transfer Wire Arc process, which is finished with diamond hones and deck plates, helps make a dimensionally accurate cylinder. This facilitates the 5.8's tight piston clearance, which helps promote a tight piston ring seal. SVT also notes the 5.8's 93.5mm bore is the largest possible in this block.