2mm will make the different already. More air to go in to the air chamber and combusion room. That's why some bore it until 64 or 67mm... After market TB like Jun is 70mm at inner diameter. But bigger doesn't mean better, big enough for ur engine OK lar. Don't tell me a stock b16a is going to put a 67mm or 70mm TB.
wazzup yall 7sifu...normaly if yall change da back box exhaust wut happend with da catalytic converter...did yall change to new one or just take it off??ist ok to take it off or just leave it there?..coz i read one...