Yes, a car can technically run straight piped without catalytic converters or oxygen sensors. However, it is important to note that doing so is likely illegal in many regions due to emissions regulations, and can result in hefty fines if caught by authorities. Additionally, removing the catalytic converter and oxygen sensors can also have negative impacts on the environment as it will increase the amount of pollutants emitted by the vehicle. Furthermore, running without oxygen sensors can cause the engine to run inefficiently, which can lead to decreased performance and increased fuel consumption. Overall, it is recommended to keep the catalytic converter and oxygen sensors in place to maintain compliance with emissions regulations and ensure optimal engine performance.