THESE ARE A VERY HEAVY GAGE STEEL MUFFLER YOU WILL NEED TO KEEP YOUR STOCK HEAD PIPE AND MAY NEED A HEAD PIPE TO MUFFLER PACKING (OUR_#262F) (SEE_#11_IN_DIAGRAM) IF YOUR OLD ONE IS BAD 078503 @ *MUFFLER_PACKING ATC250ES_ALL S90'S_ALL_WITH 18391-ML8-000 1/22M (262F)EXHAUST PACKING ATC250ES '85 BIG RED, ATC250ES 86-87, ATC250SX 85-87, CT125, S90 262F