I have a set. They fit nicely, but it takes some fabbing with the flex pipe, because the OBX headers do not come with a replacement flex pipe. They sound great, and perform very nicely, they are the cheapest header out, but the fabbing of the flex pipe might throw you a little more over than you may have originally intended.
Uh, this is the Mazdaspeed 3 forum. Headers on a turbo engine? Maybe moderator can move this to the correct forum.