Size of stock cat

paintballrocker · Post by **paintballrocker** » Sat Jun 05, 2010 9:59 am

My stock cat is bad; rattling, loss of power, shitty gas mileage. anyways im going to order a hi flow cat and just need to know what size inlet/outlet i need so it fit the factory exhaust. im considering the magnaflow spun cat, would that be a good choice?

thanks

also when i take it to the exhaust shop i was thinking of having them delete the pre cat and replace it with exhaust pipe, would that be a good idea? i dont want to set off a code, but if it can be deleted id like to do it

F9K9 · Post by **F9K9** » Sat Jun 05, 2010 11:07 am

What's your mileage? Under 80K let dealer fix it.

paintballrocker · Post by **paintballrocker** » Sat Jun 05, 2010 11:50 am

i wish mine had 80,000 haha. mine sadly has 147,XXX

F9K9 · Post by **F9K9** » Sat Jun 05, 2010 4:38 pm

Well, since Brule and I are running 3" cat back exhausts, I believe the the cats are 3" in and 3" out"

Post by **HenryJ** » Sat Jun 05, 2010 4:41 pm

Yup! 3" in/out high flow. The pipe is necked down to 2 1/2" fore and aft.

paintballrocker · Post by **paintballrocker** » Sun Jun 06, 2010 1:31 pm

ok so the stock size of the inlet/outlet of the cat is 3"?

F9K9 · Post by **F9K9** » Sun Jun 06, 2010 4:23 pm

HenryJ wrote:Yup! 3" in/out high flow.....................

paintballrocker · Post by **paintballrocker** » Mon Jun 07, 2010 7:01 pm

wow i cant believe i missed that. lol thanks

F9K9 · Post by **F9K9** » Mon Jun 07, 2010 7:22 pm

paintballrocker wrote:wow i cant believe i missed that. lol thanks

Don't feel bad, I do it all the time!

rlrnr53 · Post by **rlrnr53** » Wed Jun 09, 2010 5:21 pm

CRS syndrome?

paintballrocker · Post by **paintballrocker** » Sat Jun 12, 2010 7:50 am

well my new cat came in thursday. im pretty impressed with JEGS, i ordered it tuesday and it was at my door after work on thursday. the shop is gona get me in friday the 18th. do you think it would be a good idea to have the pre cat deleted?

F9K9 · Post by **F9K9** » Sat Jun 12, 2010 9:51 am

Wouldn't hurt.

Jongo88 · Post by **Jongo88** » Sat Jun 12, 2010 12:34 pm

I would... And I did....

paintballrocker · Post by **paintballrocker** » Sat Jun 12, 2010 12:38 pm

does the pre cat affect emissions? because the guy said he isnt sure if he could legally delete it if it does because of the emisions laws in PA. but he said he'll look at it friday and see if it can be deleted

killian96ss · Post by **killian96ss** » Sat Jun 12, 2010 1:23 pm

It is illegal to remove ANY part of the emission system including the pre-cat. A lot of the automotive forums out there do not condone or allow members to talk about removing emission equipment because it is a violation of federal law. Most shops will not remove a cat because of the liability, but there are still plenty that will do it. The pre-cat is not needed to pass tailpipe emission testing. It is really only there to reduce start up emissions while the engine is cold. It also helps prolong the life of the main cat by heating it up faster.

Steve

F9K9 · Post by **F9K9** » Sat Jun 12, 2010 5:12 pm

Steve lives on the left coast and you live in PA. Each state has their own laws and inspection regulations that are in addition to the fed rules. Research PA inspection rules to be sure. Or we can discuss the current AZ reg that echoes the fed law and is so "in" to whine about.

fallvitals · Post by **fallvitals** » Sat Jun 12, 2010 6:11 pm

F9K9 wrote:Steve lives on the left coast...

I got a chuckle from that.

border man · Post by **border man** » Sun Jun 13, 2010 3:53 am

F9K9 wrote:Steve lives on the left coast and you live in PA. Each state has their own laws and inspection regulations that are in addition to the fed rules. Research PA inspection rules to be sure. Or we can discuss the current AZ reg that echoes the fed law and is so "in" to whine about.

You ain't going to hear me whine about it

F9K9 · Post by **F9K9** » Sun Jun 13, 2010 5:58 am

border man wrote:
F9K9 wrote:...............Or we can discuss the current AZ reg that echoes the fed law and is so "in" to whine about.

You ain't going to hear me whine about it

paintballrocker · Post by **paintballrocker** » Fri Jun 18, 2010 9:07 pm

well i got the new cat put in today, no more rattling lol. but i have a odd Q now. since the new cat was put in i put 30mi on it so far and ive noticed my exhaust tone has gotten alot quiter and higher pitched, it used to be a nice deep tone but now can harrdly be heard. any thought as to why it did this?

F9K9 · Post by **F9K9** » Sat Jun 19, 2010 6:34 pm

paintballrocker wrote:...........................any thought as to why it did this?

Not a clue.

paintballrocker · Post by **paintballrocker** » Sun Jun 20, 2010 1:46 pm

me either. im stumped

killian96ss · Post by **killian96ss** » Sun Jun 20, 2010 4:41 pm

Did you have the pre-cat deleted? Is the new main cat bigger than the stock cat?

Steve

roadrunner · Post by **roadrunner** » Sun Jun 20, 2010 6:32 pm

I'd venture a guess that since your old cat was rattling it may have suffered internal damage causing possible bypass of exhaust internally which would cause it to have a deeper tone. Kinda like having the difference between a partly empty can (old cat) in the system versus a fully deadened (new cat) new part. Us old timers used to gut out glass-pack mufflers causing them to go deep and loud in the same manner. Empty chamber in the exhaust line=less back-pressure and also a larger sound chamber giving that echo-deep note.

paintballrocker · Post by **paintballrocker** » Sun Jun 20, 2010 7:13 pm

Did you have the pre-cat deleted?

nope cause of emissions testing

Is the new main cat bigger than the stock cat?

not sure, i know the new cat is smaller in length. its 3' in/out with a 4" body where the honey comb stuff is located

Kinda like having the difference between a partly empty can (old cat) in the system versus a fully deadened (new cat) new part

thats what i was thinking, but i liked the deeper tone

dozer1530 · Post by **dozer1530** » Wed Aug 04, 2010 5:45 pm

dose anny one know how much it would cost to get a new pre cat and new main cat from dealer cuz i only have 81000 miles on my cc and i think mine are clogged

Post by **HenryJ** » Wed Aug 04, 2010 5:59 pm

The precat is known to be a "problem child". Personally, I'd just eliminate the precat if at all possible. Yea, yea, I know "...illegal to tamper with emissions components." The main cat will still pass the sniffer tests and be as clean as it was originally.
If you are required to pass a visual inspection, then ditch'n the precat may not be an option.

I do not know what the precat, cat and piping might cost from the dealer. If I had to guess and if it is available, I bet it is close to $2000 or more. I know that a late model full size runs about that much.

dozer1530 · Post by **dozer1530** » Wed Aug 04, 2010 6:10 pm

but i think i have a sensor going into my pre cat? i just looked and i didnt see one im gona see if i can find a shop that will cut it off and add a new pipe in its place

Post by **HenryJ** » Wed Aug 04, 2010 6:51 pm

Two before and one after the main. No sensors in the cats.

A shop can not remove the cat. Legally they can only replace it. In the case of the precat they can provide a pipe to replace that section if it is missing. They don't have to know a precat was there.
You may find a sympathetic shop who can help you, but don't count on it. They may not wish to risk the consequences.
Having it tested and then contacting GM customer service for a good faith replacement might be another option? Dodge warranted their emission parts for 12 years unlimited mileage on some models.

dozer1530 · Post by **dozer1530** » Wed Aug 04, 2010 6:52 pm

so if i can find some one to cut it out and add a pip were it was it wont give me a dash light?

Post by **HenryJ** » Wed Aug 04, 2010 6:59 pm

dozer1530 wrote:so if i can find some one to cut it out and add a pip were it was it wont give me a dash light?

Pre-cat Delete???

Plugged Pre-cat

No problems in six years here.

border man · Post by **border man** » Thu Aug 05, 2010 3:53 am

Time for a sawzall. Dozer to muffler shop "My exhaust pipe rusted through right about here.... can you replace the bad section I cut out....."

dozer1530 · Post by **dozer1530** » Thu Aug 05, 2010 4:41 am

i wish that would work i went two 3 places already and they keep telling me no if anny one is in the houston or sugar land tx area and knows a place that will do it plzz let me know

Post by **HenryJ** » Thu Aug 05, 2010 4:43 am

Do it yourself. Sawzall, pipe, and two band clamps.

dozer1530 · Post by **dozer1530** » Thu Aug 05, 2010 4:44 am

what you mean. oo ok so i cut it off and then get a pice of pipe that fits and the clamp it on ?

Post by **HenryJ** » Thu Aug 05, 2010 5:50 am

Yes. Use stainless steel band clamps. That will work until you find a place to weld it up.

dozer1530 · Post by **dozer1530** » Thu Aug 05, 2010 8:12 am

ok i just got back from dealership cuz i had that recall on the tail gate cables they didnt have any

. but i had my cats chekt out and they are fine it was a program issue they redid it and its ruining great now. im gona fill up next week and chek the millage

Post by **HenryJ** » Thu Aug 05, 2010 8:38 am

Sounds a little fishy to me.

dozer1530 · Post by **dozer1530** » Thu Aug 05, 2010 8:52 am

i had a tuner on it and then reloaded my stock and i kep getting an err so i unplugged the battery. then i tried angian and it worked. but when i took it to the dealership it showed i had some errs so cuz im still under warranty he redid it and he said if i want i can come back to marrow and get a new pre cat put on. i trust them cuz the mechanic is my brother in law.and i use hi, every time i have a warranty issue and he all ways gets it done. what he did was put a hole on each side of the pre cat like my dad had told me to do and see if the presher was the same and we did this to the main cat as well
so tomorrow ill just have a new one put on any way. hes just gona warranty it out and when i find a shop ill get it cut out. i ask if he could but hes not the welder there lol

Post by **HenryJ** » Thu Aug 05, 2010 8:54 am

Ok, the details make more sense.