2.25 exhaust or 2.5 for a 3.0 v6 infiniti j30?

[live life to the fullest]

i wanna do a full exhaust system on my car that's a non turbo should i go with a 2.25 or 2.5 system? my car has two 2.25 stock cats but im gonna remove them and add 2 hi flow cats that are 2.5...