I know you only list it for Mac longtubes, but what will it take to make it fit bbk longtubes? From everything I've found, it's my favorite sounding x with te mufflers I'm picking up. Car is an '01 GT if that means anything.
Some customers have got that X pipe to fit the BBK's, but I'm not sure what exactly was done. If I had to guess, it would be the collector spacing is different, so you may need to widen or close the spacing of the X pipe inlet.