Yup. Umm fuel economy, yeah maybe it helped, but i don't really know, but it's a bit noisy. Yes, could be just removed afaik and replaced with a straight pipe, but am not sure what happens if you have a 2nd O2 sensor after the cat (sure could affect it's readings). Din't fail me when I got my emissions test 2 months back. But again I wouldn't recommend you polluting the air around you with toxic fumes and the noise