The 2.4 engine has a very strong bottom end girdle that makes it extremely free of flex. Flex in the block kills more engines at extreme levels than just about anything else. In fact, it seems the 2.4 is stronger than the Common Block 2.5 in your Spirit. Pistons are of comparable quality to those in the 2.5 and everything else ranks up there as well. You should have a long happy life with your new PT.