catalytic converter

I have a 92 Cavlier 3.1... i took it for an emissions test and it failed so i was talking to my dad and he said it was probably my catalytic converter i went and picked one up. i got the old one off with a hack saw but the new one i got is half as small as the original so i also bought some more pipe and some adapters. i put the new one on and when i start the car up it's really loud. i would rather fix the problem myself or would it be better to take it to a shop.
Thanks, Dan

Did you replace the muffer by mistake? The muffler is towards the back of the car. The cat is more towards the middle.

Presuming that you did replace the cat, was the pipe diameter the same? Was it a universal replacement or was it more of a direct replacement make particularly for your car? Changing the size/shape/pipe diameter/flow rate/etc can change how your car sounds (as well as performs).

Also, how did you seal up the joints? Did you use muffler clamps or did you weld it? If you used clamps, it's also possible you are hearing an exhaust leak.

i replaced the cat......i used clamps to seal it....after i made this post i checked to see if the clamps were tight enough and they were a bit loose so i tightened them up and it is starting to sound better but not as good as i would like.... i might take it to my dad's and get him to weld the joints to see if that helps.

thanks for the help very appreciated

the noise is probably just the pipes not fitting quite right. For a quick fix, I'd say go to the store and get some of the putty stuff they you can put on an exhaust system that hardens. It'll work for your purpose of sealing any leaks.

As for the size, you're fine. You got a modern catalytic converter, they're much smaller and more efficient than the stock one that was on your car.

I'd still weld it over using clamps/putty. Over time the putty can crack and fall out. Weld, properly done, should't. I just replaced my cat in my minivan. Took a muffler shop a whole 15 minutes to do from start to finish and cost me $50 for the welds.

shops usually won't take them off

shops usually won't take them off
Not true. I had my exhaust on my 97 cavi done. They replace the cat and then i had them put a custom cat-back exhaust. So some shops do take off cat. converters. Unless u mean take them off completly?

It's illegal for them to remove them. However if it becomes damaged or needs repaired, they are free to take them off. In this case, the OP wouldn't actually need them to take it off...just weld what is currently there together.

It's illegal for them to remove them. However if it becomes damaged or needs repaired, they are free to take them off. In this case, the OP wouldn't actually need them to take it off...just weld what is currently there together.No i understand that they cant remove them but the can change them which was my point.