the gp has over 164k on it just isn't getting the fuel mileage that it once did. when i did the tune-up around 100k, it just didn't seem to help as much. i've read where people have changed out their cat and it made a huge difference in power or fuel mileage and that is what i'm looking for!

i asking if there are any recommendations on where to buy one to replace it. i am not really sure if i need to spend a lot of money a bigger pipe since the car has so many miles on it and don't plan on modding it. if it isn't that much more, then maybe it would be worth it.

it would be nice to get one with out the u-bend already. i went to the local muffler shop and had it taken out 2-3 years ago, but the guy didn't do it right and it would scrap sometimes and then o2 sensor went out.

anyways, if there are any places that you can point me to on getting me a replacement would be great. i know there are many of you that have looked at them so i hope that your input can help me.

i just put in catalytic converter on google and some place came up and the prices were not that bad for the whole thing, but it did have the u-bend.

i would like to have a good high flowing cat though and i'm not sure if all of them are this way or just certain ones.

thanks for any help :rolleyes:

look up any of the AM performance stores that are W- body specific and price out a whole DP/cat setup, should run you around 250-300 for the whole thing. then you'll need new gaskets for it, but after you put it on, you'll notice a difference in throttle response and you should end up with between 1 & 3 MPG over stock, due to the increased flow (that's what I ended up with when I put my JimmyC on)


www.zzperformance.com
www.wbodystore.com
www.grandprixstore.com

check these guys out also :
www.hoganperformance.com

I'm sure that if I missed something, someone else will chime in

ZZP's bolt in w/ hi-flow cat is $199.99, without the cat it's only $129.99 IIRC. Either way it's pretty cheap, and OEM cats are pretty expensive.

x2, if I were you I would order the 2.5" D/P from zzp with a cat. Bolt in. That will come with the u-bend replacement and everything.

3" all the way!

oh the 3" is only 10 bucks more...do it...

2.5 will be restrictive if you keep modding. go 3"

3"!!!

Go 3 forsure. I did mine last week with a Manga High Flow. No diff in my mileage but it seems more powerful in the high end and sounds better even with stock mufflers. Beware tho, I have had to clear a code since due to the cat, so u may need a O2 spoof or tune that deletes the 0420 code.

If you decide you want OEM, I have my stock cat (only 35k miles on it).

I was going to cut it from the stock downpipe and ubend and get a $50 credit from zzp for it. But if you want it, I'll sell it to you for $50 instead.

First off, I want to thank everybody for their input!

Hey UMfan, I appreciate the offer, but I think that I would rather just go with a whole complete downpipe. Like I said in my original post, I had the u-bend taken out but put back in due to them not doing it right so I just don't think it would be a good install. Plus by the time I pay shipping and them to install it, I could probably pay another $100 and get a 3" dp with out the u-bend!

Ok, it looks like i want to go with a 3" down pipe that is a bolt-in with a cat and no u-bend! I believe that ZZP has the best deal on it. I just want to ask you to make sure that this is what I need to order. I selected these options:
1xZZP downpipes
Model: 3 inch bolt in With Cat
Option 1:Interlock flex
Option 2:None selected
Option 3:Add front and rear gaskets
Option 4:Send me a prepaid return label

I chose not to go with the 304 stainless dp because I don't really think the extra $50 is worth the investment. What do you think? Like I said, I plan on doing no modding to the car and it has 164k on it and no major work has been done to it. I just think that over the almost 10 year period and reading about them that it would not hurt to change it out! Is going with the regular 3" dp going to cause me any problems? If I have too, I can go with an O2 spoof later, but that is only if I have too!

Another question I have is about the gaskets. I chose add front and rear gaskets, is that right? All I need is gaskets and not doughnut type gaskets or anything?

Also, is there anything that I need to know when putting this on or to do in preparation to take the old one off and put the new one on?

I'm sorry for asking all these questions, but I just want to make sure that I am getting the right thing before ordering it!

I plan on sending the other back though since I have no use for it like UMfan and getting the $50 coupon. If possible and anybody can use the coupon, would anybody be interested in buying it for less than what it is worth maybe! I doubt I have any use for it since I do not think there is anything I need to buy with it.

Thanks again

if you can, i would spend the $ and get the 304. i ahve seen a rusted out one, and im sure you get your share of snow...which means road salt and rust. But other than that, be ready to fight with the bolts, use some PB blaster

Since we're talkin cats here...

On my stock GT, if the cat were going bad, i would be getting an idiot light, right? I believe my car is losing performance, and the mileage has never been as good as yalls. I am also quick to remind everyone that I am at 4300 feet ASL, so I also believe that some loss of power and efficiency has to do with altitude. If the idiot light doesnt shine if I have a bad cat, how can I have the cat checked? Thanks for lettin me jack the thread and for any advice yall can offer.

A rotten egg smell is the first thing I usually look for when driving if I think my cats failing, past that, you can ask a muffler shop to look mebbe? Not sure heh.

Snow, either get the rear o2 dummy thing or get someone to delete code P0420 from your PCM too, cause your idiot light will prolly light up almost daily. (Mine has been). If you dont have a scanner to shut it off with it gets annoying.

Richard, a couple years ago when I went in to get the u-bend taken out, the guy was saying that I should replace the cat. Something about the amount of heat that was coming off of it can show that one is clogged or something that the guy at the muffler shop said. I do not know if it is true or not, but you can kinda of smell a different smell from the car from time to time!

Fiin, I think I will try it without it and see what happens and maybe I will get lucky but if I have to have it, then I guess I will get one cause I do not know anybody with a scanner to shut it off. If I do have to get a o2 dummy thing though, who has the best price on them?

http://www.3800performance.com/Merchant2...roduct_Count=16

I beleive is what you'de need. (I am supposed to be getting my PCM tuned up locally or I would be getting one too lol)

I have one more question. If I buy the bolt up 3" downpipe from zzp, am I going to have to have the end welded on or anything welded on or will it be a direct replacement and bolt up to the manifold and back section of the exhaust system. I just did not know since it is 3" and the stock system is 2.5"

It will bolt right in. The downpipes from ZZP have a reducer section that is 3" where it bolts to the exhaust manifold, but it reduces to 2.5" in order to match the catback. you should be good