My mechanic is warning me that because my car is running so rich (enough to lose 7mpg) he is worried that the catalytic convertor will get plugged up and he has heard horror stories about this happening to other people and ultimately it ruins there engines....I don't want that happening to mine!! He said I should look for a straight pipe to buy but I would love to hear your opinions...is there a cat I can buy that won't get clogged with a rich a/f mixture? Do I just need to get one of those $30 cats off ebay as a temporary fix until I get the MSns on there to fix the a/f problem? What would you do...