I have a 2000 Honda Accord V6 Coupe.

I am getting exhaust put on soon, and I wanted to ask you all what size piping I should get. Some guy said I should stay with my stock piping and get new mufflers. 2" piping is stock. I wanted to get 2.25" or 2.5" piping, but the guy said I would lose pick up speed. Is this true?