Ok in my never ending world of strange car problems I thought I was done. I changed my alt today and it solved my flashing battery light problems. BUt pieces are getting loose in my cat and I am wondering the problems this could cause. MY car isn't hesitating but its backfiring every once in awhile mostly in third while decelerating. At idle I hear what I could be mistaking as detonation but it not very pronounced. I have done all the basics and the only thing not changed is the fuel pump. Car still pulls strong and the problem is intermittent its fine now but not fine later. The problem feels like if someone added a few hundred pounds to the car, it feels like its still pulling hard but not the way it should. Will changing the cat solve this. Help please I'll be :beer: till you guys respond.

 

My old rex had the b pipe rust out. The loss in back preasure made a sound much like detonation when it back fired. Just a popping, but a muffled one. That and the loss in back preasure made it slow as a dog. Seal it up, and I'm sure at least half your problem would be solved.

 

My old cat was dead and falling apart. I got a high flow Catco Cat and it has worked out fine, really good quality, no rust. And I don't really thing it's that much bigger than stock so it won't mess up your backpressure really.