help me

hello I'M SHOPPING FOR SOME FLOWMASTERS FOR MY 1968 FIREBIRD I DON'T KNOW WHICH ONE'S ARE GOOD FOR MY CAR I BEEN CHECKING THIS FLOWMASTER CALLED 40 SERIES BUT I THINK THEY WOULD BE TO LOUD FOR A DAILY DRIVEN CAR CAN U HELP ME PICK OUT THE RIGHT FLOWMASTERS FOR MY CAR ?

I don't know what series would be good, but don't use all caps, it means you're yelling. Punctuation is good too...