The only headers I had any experience with are the TTI's. W2/W5 X 1-7/8 But they would cover part of the center ports. I actually used the TTI flanges but had to completely rework the center ports and all the bolt holes were oversize, so I had to rework that too. Plus most one piece headers are a PITA to install. So, in the long run it's better for me to make my own.