ANSI or Ansa? Any way, you can gain some clearance by loosening the three bolts that connect the rear to the mid pipe. In a perfect world the two flanges should be parallel to each other, I would check that first, if it is parallel and still hitting then you can slightly tip the rear downward bringing the two rear portions off the flanges closer. It will still seal even if not parallel.
as Vabene says, you can get a lot of adjustment through the triangular connection between mid and rear section....that fat donut gasket seals well.
Loosen the 3 bolts and have someone hold the ansa tip correctly at the back of the car, as you slowly tighten the 3 bolts, each a little at a time.