I checked online to see the difference between 409 stainless (SVT) and 304 stainless (Sport). Here's a quote I found.
The most common stainless steel used by muffler shop is the T-409. Borla use T-304 stainless steel grade. It's why the price is so different. A Borla looks great and will shine for ever! T-409 is good for peoples who live where there are no calcium or where the corrosion is not a problem. T-304 is for north american and canadian peoples who want to keep their cars for more than 3 years in a corrosive environment
2011 Mustang 5.0 sterling gray, manual, Brembo, 3.73, HID, security pkg, Canadian model. Borla S-Type axle-backs, Airaid CAI and Bama tune. Barton shifter and bracket waiting to install.