aftermarket unequal lenght shorty headers. Before you ask what brand, if it was a name brand that they were proud of there would be a metal plate welded to it, or they would be laser engraved somehow to mark them. They look almost like a mac style though with the separate header flanges for each pipe, rather than on big one. IIRC that style is known to leak a little easier assuming that the one piece flange is nice and flat. You might try to give each bolt some pressure to make sure they are all tight.