ok guyz..l know this has been covered abit..however i'm still not finding what i really need

engine is a d16a8 in my civic...
l got headers and a muffler...however i wanna know my ORIGINAL size cat back....

i heard that 2" is better all round and 2.25" is better for top end...
now my question is....which is better:
2" MENDREL BEND OR
2.25" PRESS BEND ???

is there anything in between that?? what is the "best" diameter for all round performance ?