I recommend staying within a specific brand for exhaust products. If you go with MAC headers, get a MAC H pipe. If you go with a BBK X Pipe, get BBK headers.
I have a BBK Highflow H pipe with Cats, it didn't fit the factory headers for ****. It was a couple/three inches off easy. The hangers were welded asymetrical, and at uneven heights, and the one of the pipes was rotated too far causing a misalignment.
I got 2 at my place, both were the same. Actually, Summit screwed me on the deal. They boxed up the part I sent them in a different box and sent it back to me. Lame. What can you do though?
