Thread: Need help!

There is a rattling in my exhaust system. Sounds like resonator and it is setting off my SES light which I know is the o2 sensor. The only problem I am having is that my exhaust is the magnaflow performance cat back system and I can't find anyone even magnaflows website who sells just the resonator. Any information or suggestions on an alternate fix or where to buy would be great. Also it is starting to affect the performance of my GTP when I punch the gas sometimes its making the engine hesitate and bog down. Thanks again.

If your second 02 sensor is causing the SES light then its the cat not the resonator causing the bog down. The cat is probably clogged which would explain everything except possibly the rattling noise unless it was damaged in some way.

Ok Thanks for all the help.....I am going over to a buddys right after work putting the car in the air hooking up the computer and getting this thing fixed before bigger problems arise. First gotta see if its the cat or resonator as they will both do the same thing if buggered up so I am told. Thanks again,

In our cars its just that much more common for the cat to be clogged and cause this.

The rattling almost sounds like a heat shield. i did just buy the car and it is my first gm product so I am new to them but have had heat shield problems in some of my other vehicles. I will have to see when its in the air I guess. Does anybody know a way to tell if its the resonator or the cat? The resonator is only a year old and it is part of the magnaflow system installed. The cat who knows my guess is original.

It is a 2000 GTP with 155k.

You could in theory unbolt the resonator and pull the catback off and see if the rattle is still there.

To test the cat I'd pull the downpipe out and see if the car drives better. The code won't go away with no downpipe considering there'd be no cat or rear O2 sensor.

I'd personally invest in a new downpipe with a highflow cat.

ZZ Performance

$200 for a bolt in 3" with a magnaflow cat.

Typically one of the next upgrades when looking to drop pulley size. Two birds with one stone?

I have thought of the down pipe thing and if I am replacing parts which I know I will be I am going to do the 3" down pipe but I may change the whole exhaust system as what is the point of having a 3" go to a 2.5" and back to a 3" tip I don't know why magnaflow did that instead of going 3" all the way maybe noise reduction who knows seems like they made more work for everyone there....Thanks for the reply.

With our cars the restriction is in the downpipe and forward section of the exhaust. The typical figure most claim for the catback is 350 WHP being where it starts to become restrictive. The only point in investing back there is sound.

3" downpipe will help with one major issue, the u-bend where the second O2 sensor is. Gets to be 2" or less IRRC. Front exhaust manifold is also pretty bad.

Edit: I see how it works now... You don't need more than 2.5" piping back there. A single 3" pipe is the proper size for a fairly built 350, not for a lightly modded 231 cu in V6

Can you suggest which pipe to buy from zz performance. I noticed they have one with a cat is it any good just incase I need one. Im guessing I just need the basic 3" not shorty or off-road.

Its not a "good" cat so much as one that cleans well enough. It does however flow very well. Its a magnaflow unit so its going to be comparable in quality to your catback.

Do you want to have a cat? I mean some people know people to still be able to get their plate stickers without an e-test but if you don't want to deal with that get a 3" catted bolt in pipe. You could jump for the stainless version if you plan on keeping this car for more than 10 years or prefer the idea of not having to replace that.

Also could jump for the weld in if you've got the skills or someone to weld it in for you.

I could weld it in I guess. I am thinking of stainless the rest of the way it only makes sense sure its a bit more money but I wont have to think about it again..... I hope. I would love to get rid of the cat and could talk to some people but then again the hassel so I am going to do 2.5 the whole way I don't see any need for more and the benifits of going bigger don't outweigh the time and cost of getting it to fit. going to get a high flow cat and I should be set. Thanks again for your time I greatly appreciate it.

3" downpipe really is the only way for a GTP unless you want to stay stock. Not a problem.