I swapped in a new MAC off-road H on a friend's car and the driver's side flange that meets the header will not fit snugly. The nut is as tight as I can get it, but it still has a huge exhaust leak. There is a spacer on the header stud that is in the way. I am assuming there is a way to take this off so the flange can fit tightly. How has everyone done this? BTW, this same thing happened when I swapped an h-pipe on my '01 GT a couple years back.