Does a 2006 Ford F-250 6.0 powerstroke have to back pressure or can you run strait exhaust?

A 2006 Ford F-250 6.0 Powerstroke does not require back pressure to function correctly. While some minimal back pressure is naturally present in any exhaust system, adding restrictive components specifically to increase back pressure is detrimental to performance and can even damage the engine. A straight-pipe exhaust system is perfectly viable, although it will likely be louder.

However, it's crucial to understand that removing the exhaust system's components, particularly the diesel particulate filter (DPF) and exhaust gas recirculation (EGR) components if still present, can lead to engine trouble codes, potential legal issues (depending on your location and emissions regulations), and potentially damage the turbocharger due to increased heat and exhaust gas velocity. A properly tuned and well-designed exhaust system (even a straight pipe setup) should account for these factors to avoid causing problems.