Upgrading the turbo in your OBS 7.3L Powerstroke is one of the most rewarding upgrades you can install. The power increase throughout the RPM range will increase the "smiles per gallon" factor substantially. The experts at Industrial Injection have the perfect upgrade for your truck, the Billet 66mm XR1 Series Turbo. This turbocharger comes with an upgraded Billet Blade Technology 66mm compressor wheel and available in an .84 or 1.15 A/R exhaust housing. A rule of thumb for selecting an exhaust housing size is the smaller the size, the quicker it spools. The .84 housing will spool faster than the 1.15 but you may notice higher EGT's in elevated RPM's. The 1.15 ratio will spool slightly slower spool times but lower temps and better efficiency during elevated RPM's.