You might want to try pricing some LT's form HOOKER.
Hooker has been doing vette header's for a long time.
, going back to the Stingray day's w/ the Hooker side mounted header's.
and 4" tubes.
I believe you can get the Hooker LT's, stainless hot dipped coated header's for around $385.00 which is very reasonable..........vs LG/Lt's stainless as on my Mallett for $7K +. And is there truly that much difference in performance for a street driven car? H..ll no.
However, w/ any vette and header install, do by all means install a cold air induction system to notice a big difference. The Varrram system you mentioned earlier, is the one I have w/ Blackwing filter. VERY good system.
Good X pipe w/ or w/out cat's for sure.
Because we have no state inspection up here in central Fl, my Mallett has no cat's.