was up

i want to put a i highflow cat back on my car but i want to know whats the best diameter i can buy the piping in order to get the most performance i have the option from 2"-3".... the guy is telling me to get it 2 inches in order to get the most back pressure but i want to make sure with u guys........i have a 95 honda civic ex.....thanks

i've always been told 2-1/4" is best n/a but for fi 3".....i could be wrong about fi....but go with 2-1/4"

yup 2 1/4 is what i say 3" for F/I then agian bigger motors need bigger exhaust but thats another story