Having no experience with TTI headers I can’t comment on them. I do have a set of T/A headers on my ‘71 Demon (W2’s with 4spd). I had an issue with #3&5 hitting the steering shaft when I first bought them...probably about 10 years ago. They fixed the issue without any problem. They are slip fit as mentioned and have tabs to bolt the tubes together. I assume yours do as well. As with any header I’ve ever installed, you will probably have to do some “clearancing” to get to fit your car. Would I use them again...definitely.