1. Stepped headers are a fad, unless you understand what you are doing and your engine is developed around them. Even then it’s a crap shoot.
2. Take a good look at the collectors. One of the worst designs there is. It’s horrible. If you don’t think there is power in the collector then you just haven’t done any research or testing.
3. Getting all the tubes above the steering linkage makes working on the car a nightmare. Getting a transmission or a scatter shield with a TTI header is a giant PITA. There is no reason to do that.
4. Back to the collectors. TTI points them inward, which again is a problem. It makes fitting exhaust more problematic (rather than less so as TTI claims) and makes everything closer to the transmission.
My dad dies when I was fairly young, so I hung with my uncle (his brother). I watched him and rode with him in cars with all brands of headers and even deep pans and never once did he smash his headers or pan. My last A body was a 69 Dart with a 4 speed. It came with Hooker headers and a Moroso deep center sump pan. I drove that car my last year in high school and all through college and never dented the headers or the pan. The car was easy to work on too. I could get to all the plugs and getting the starter out was a breeze. Again, I would use manifolds before I over paid for TTI headers.