I picked up my RS on Monday a 2017 , with 50,000 miles. The head gasket has been replaced by ford, it has a Cobb composite cold air intake kit, and after market exhaust. I dunno if it is a full exhaust or just a slip on yet. It is at the dealership already for a check engine light that posted on my test drive. I had the selling dealership check the code ,and wanted them to fix it. They checked it , and i was told it was fixed. But i am pretty sure it was just wiped and not fixed. So it came back on the next day. I got the code it was a 300 code and a couple others that i can't recall right now. The paper they are written on is in the car at the Ford dealer. I got no list of mods from the used car salesman, because they were not informed of any. They had no idea what an RS was until this sale.. So hello everyone ! I am prob gonna be asking a ton of questions. First off , will a Cobb cold air throw a check engine, and same question for a slip on exhaust?