Best Exhaust Size EG3

Hi
What size backbox would be best for an EG3 (Civic 1.3 dx)? I read somewhere that a car with little power like mine shouldn't have one bigger than 2" as it will lose power instead of gain power, is this true? Thanks.
What size backbox would be best for an EG3 (Civic 1.3 dx)? I read somewhere that a car with little power like mine shouldn't have one bigger than 2" as it will lose power instead of gain power, is this true? Thanks.