Header fitment... Well not really. Idk who Doug is but I suspect he also owns Milodon. These are D453's and I had to 'massage' 5 of 8 header tubes. Idk why they don't include a hammer with every purchase.
I have the same borgenson box as you with TTI headers. I had to cut to make relief cuts in multiple tubes. I think you came out way ahead of me. Needless to say I'm not impressed with mine at all. Car looks great Btw.