318willrun has the adapter also, and it looks like he had a mile of clearance. The TTI's are step headers, that start out with 1 5/8 tube, and then step up to 1 3/4. Dougs are 1 5/8 all the way. The TTI's have one slip tube on the drivers side to go around the torsion bar, but I don't think the Dougs headers have any slip tubes on the D453's.
