I have the factory black stripes on my car (SGM)...you will have the same colour.
The only stripe options you can get are black and the silver/white colour. I'm not sure how/why yours may look brown...but they are black.
2013 Mustang GT - 402A GT/CS - 6R80 - Glass Roof - Engine Block Heater - SGM Exterior - CB/Miko Interior
Steeda Adjustable PHB (Street) and Steeda PH Brace, Stainless Works Retro Catback Exhaust...