Q: Wrong Flexpipe size repair

Shortening the flex pipe should not have an affect on performance of the engine. The length of the pipe on a daily driver is not something that is very critical to operation. In a race car it becomes more important because the exhaust will be tuned for maximum performance when being used at its peak for long periods of time. In essence, a daily driver won’t need to use as much of its potential flow, for nearly as long. With that being said, I would be sure that the shortened section is not causing problems in other ways. I would be sure that the shortened section is not causing clearance issues, undue stress on exhaust hangers, or other issues that may arise from the system being shorter than designed. If this is something that you would like to have looked at, contact a certified mechanic, like the mobile mechanics available at YourMechanic.com.