the main factor in almost all of our bottom ends letting go is the rods, so yes they are the weak link. there are some ba's in the 400's without rods. give me one person who would recommend that. as for the pistons, here goes. from what im led to believe, acl was the manufacturer of pistons for ford and many other car companies for that matter. im pretty sure there policy was to use a forged piston for any engine producing 100 or more hp per litre which the f6 does. mahle have taken over the piston division of acl, so there it is, mahle forged pistons. acl or mahle are not just aftermarket. they do heaps of oem as well. the part number for rods is the same between fg xr6t/f6. I know that as I rang ford myself. they couldnt however tell me anything about the pistons. im happy to be proven wrong on it. on another note, it suprises me that rdp would remove the engine from their fg to do valve springs, head studs and oil pump gears but not replace the rods while it was out. doesnt make sense. I guess they want to find the limit of them and can obviously afford to do so.