I have 3 good AMS ross pistons with 4000 miles on them. They will need new rings. These are stock bore. And are the $650 pistons they sell. They do say AMS on the top. The 4th pistons had some issues and is no good. I have 3 good ones, ill leave the rings on them but I would replace them. AMS said they could get a pistion for $150-$190 for one piston. I just have these seting so im taking best offers, i dont want to just throw them away. thanks