The TTI 1 5/8"-1 3/4" step should be considered like 1 3/4". They fit a broad range of HP output. I haven't been on a dyno, but I've run 11-teens at 117+ in a 3,540+ lb car with a 360, normally aspirated and footbraking. Mine are coated in & out and I use their X-pipe & Dynomax UltraFlos.