My Cherokee 140 was generating aluminum flakes and had the filter sent to lycoming which said it is from the piston plugs. There is evidence of some scratching on the cylinder walls when they did the bore scope and the shop said best to replace them all so I will be getting a whole new top end and upgrading to the 160HP STC to replace the bad parts. Anyone know what I should do with the 4 old cores? They are millenium cylinders.