I vote for TTI. Outside as well as inside coating options. The 1 5/8"-1 3/4" step could help HP and torque #'s a bit over the straight 1 5/8", especially when hopping the engine up. They work great on my race car too running mid-low 11's (with TTI X-pipe & Dynomaxmufflers). Easiest to install and best fitting chassis headers I ever had.
