My vehicle is experiencing exhaust fume issue where the exhaust fumes are entering into the cabin for Explorer and Aviator models (Any model with the 3.0L Ecoobost). Upon inspection by 3rd party mechanic, it can be determined that the problematic catalytic converters that are not the one piece cast was installed on my vehicle from the factory. Speaking to other ST and Interceptor owners, the problem seems widespread to every 2021 model that Ford installed the multipiece welded catalytic converters. Apparently the cast part fairs better and is not subject to cracks. The recall originally covered the left side catalytic converter but the flawed design also affects the right side catalytic converter where many owners are experiencing this issue. This has affected all 3.0L Ecoboost engine vehicles. [XXX] I believe the recall should have extended to cover all 2020 and 2021 model year vehicles. There are forum posts where owners outside the recall have experienced the issue in addition to owners having to repeatedly replace the catalytic converters post warrant as Ford continued to reinstall bad catalytic converters as part of the repair process. I have driven this vehicle for several thousand miles with the issue and did not realize exhaust was leaking until notices of headaches and health issues as CO is odorless, causing CO2 levels to reach 3000+ inside the cabin at stop lights and blows in through the vents if A/C is on. I believe NHTSA should investigate this issue further