Depends on what you want to do further down the track.
If you wanted to turbo then 2.5"-3" would be needed in a catback, but if not 2 1/4" would be sufficient, and I think the stock is 1 3/4" or 2" so really not a huge difference, just better sound and a bit better breathing.
If you wanted to turbo then 2.5"-3" would be needed in a catback, but if not 2 1/4" would be sufficient, and I think the stock is 1 3/4" or 2" so really not a huge difference, just better sound and a bit better breathing.