The TTI tubes are pretty good. Mandrel bends and a decent, fit in general. Not exactly a straight bolt on with my cars, usually took some triming and adjustment to get the fit I wanted, but most of my cars are not using the TTI headers.
On the '71 Charger, have the TTI 3" H-Pipe exhaust, and Hooker Super Comp headers on a low deck 400 block with raised exhaust port cylinder heads. Anyhow, I had to frim the H-Pipe shorter to fit. Car has the stock non-HP tail pipes that turn down, and they fit good.
On the '69 Coronet have the 2.5" X-crossover system with the chrome tips and I had to shorten the tail pipes for using the tips.
Exhaust shop quality varies, and usually the tubes are compression bent, not mandrel bends, but a good shop can get the fitment real good.