From your pic it looks like the crossover is about two inches too far to the driver side. I recently installed SD headers and mine was that far out.
Rotate the crossover to get the best combination of angle and closeness. Then, use a wood 2x4 piece between the body to force the front of the crossover to match the front header. Its a matter of shimming garbage between pieces of wood to get it there.
Looking at the header/crossover junction from the driver side will show that they meet at an ugly ass angle. Push them together and tighten to the head while having as many studs in cyl head as you can. Beat the crossover with more wood occasionally to better slide them together.
BEFORE you begin this, make sure you can slide the front header into the crossover without effort. If it doesn't, take the pipe to have it expanded. The muffler shop will tell you they split if they are expanded, but I did it because there was no option. Stainless steel actually is very ductile, but then again SD's are more like "mystery steel". The pipes didn't split. Oh and the rear header should be tightened down.
These are ugly ass headers so you have to beat them at their game.
