67 Barracuda Headers

There's lots of threads here but RRR sums up the situation for most people.
For all out performance, very very few had tested results, and it will depend on the combination and form of racing. For two to four times the cost of the TTI long tubes, custom is the answer for an all out performance effort. Look up Mark Leshenko (sp?) of Performance Welding, Calvin Elston, and there are others that have done these for A-bodies.
If ground clearence is not an issue, then Headers By Ed has designs that will work and fit nicely - but he is not building them anymore - buy the parts and build yourself.

Off the shelf - the TTI stepped header is probably the best choice due to the stepping.
I've not seen any tests on the Schumacher's small block version of the Tri-y. Its got so many differences from the big block design (which at least one magazine did compare) its hard to guess how efficient it is other than what it looks like.