my Catalytic Converter rattles. Everyone tell that my cats bad. either way i'm just going to replace it. now i get a little less than 15mpgs. after i replace it will my mpgs go up meaning i get more mpgs per gallon?

*MERGING DOUBLE POSTS*

my cat rattles if I replace will get more mpgs per gallon. what if i just take off my cat an take out the lose stuff inside the cat. would that fix my noise. will it pass inspection and emmisions next year when i have it tested? help?

 

Take the money you would spend on 'mods' and replace the cat. Mileage might increase slightly along with the lost power.

 

if the inwards of the Cat is what's rattling, there is a slight chance it is restricting Exhaust flow which would make te engine work harder..i.e. lower MPG's.
If some welds broke and there is no restriction. you will gain nothing but a quiet Cat.