Guys, i have a '64 nova with a basically bone stock 194-6 cyl in it, only modification was i removed the muffler completely and ran 17/8" (i think) pipe striahgt out the back to a 3" chrome tip.. sounds REAL good, pretty loud. but someone told me that running with a straight pipe will ruin my exhaust valves and seats becuase of temperature variations. is this true? should i install a glasspack? Jay B.