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72 Gremlin 11.03 @ 121
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Discussion Starter · #1 ·
Hey Guys. So I just got a 2000 clubcab slt 4X4 4.7L
There is so much info on this sight it confuses the heck outta me!
My truck poped code P0420 poor cat performance. So The dealer told me I need a new y pipe at 620.00 plus labor. I was thinkin for the money mabe there is a better way to go? I priced the same part Dodge quoted me from nappa my cost 330.00 but it only apears to have one cat and my truck has 3...
CT has emissions so it has to pass. but not too worried about passing visual.
Do I have to go with the y that has the 3 cats or can I use the one w/o? What do i do with the o2 connection up near the manifold on the drivers side?
Or is there a better way? Long tube headers duals w aftermarket cats? I have about 800 to spend. What would yo guys reccommend? Shortys new Y and one into 2?
I will post about what else to modify in another area.
Thanks for any input and advice.
Davis
 

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Too close for missles!
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you can get a pretty decent exhaust setup for 800 bucks. it all depends on what you want to do. if your just interested in changing the cats, just go ahead and replace them with some OEM style, or some high flows. Im not sure how well the high flows do for emissions, and from what ive heard, CT can be a real bitch about it. some shorty headers, new y pipe, high flows, and a nice muffler sounds like a good idea, and might put you right around 800.. im sure someone else will jump in that has mroe experience with exhaust
 

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72 Gremlin 11.03 @ 121
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Discussion Starter · #3 ·
The Y pipe from Nappa doesnt have the cat near the drivers side manifold...there is a O2 sensor in that cat. WHat do i do with that? Weld a bung in it? Did I post this in the wrong place? I figured i would get alot more responces... Thanks for tryin to help Spastic88
Davis
 

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2000 4.7's only have one cat, 2001's have 3. 2000 has one O2 sensor, 2001 has 4. Any good independent muffler shop should be able to install a Magnaflow y-pipe ($35 part) and Carsound/ Magnaflow hi-flow cat. ($130+ part). The factory y-pipe is a dog; only has 1 1/2" entrances at the "Y". Check out www.magnaflow.com under accessories. BTW, OEM pipe diameter is 2" from the manifolds. I went with 2 1/2" after the "pre-cats" on my '01, the Y, and a 3" exit to a 3" cat. Good for about 1 mpg improvement to boot.:banana2:
Also, '00's had 65mm throttle body, '01's and up 68mm...easy swap.
 

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72 Gremlin 11.03 @ 121
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Discussion Starter · #5 · (Edited)
01motorsport...great info! Thanks.. Ok my truck is a 00 but I am unsure of the build date. It definitly has a cat on the drivers side right after the manifold the o2 sensor sticking out of it, Also see a cat after the Y pipe. Mabe my truck is a late build date and has the 01 stuff? I would love to swap the y pipe for somthing that flows. SO am i stuck with the stock 01 y pipe? What headers should I use? seems stupid to use headers with such a restrictive y...
Davis
 

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an exhaust shop can easily fab you up a new Y-Pipe in 2.5" which will help you out a lot. then you can get some small round high flow cats put on it and retain your O2 functionality and emissions. if that's all you need then great, but for 800 you can get a full exhaust front to back which would be the best. even if you get a magnaflow catback system to bolt up yourself it would be better. don't worry about headers. they don't really help much on a 4.7 and you'll lose half your money just on those. the stock headers just happen to flow great on this engine.

if you do have the exhaust shop do a full exhaust then ask about getting a full single 3", with a new 2.5" Y-pipe. i would buy the cats and muffler of your choice elsewhere for much cheaper and just have the shop weld it all up. the 4.7 really likes single 3" though and performs well. the main thing to check for at the shop though is what type of bender they have and how skilled they are. some places just use crappy crush bends like stock which does you no good. it's almost impossible to find a mandrel bender in a shop which would be best, but next up is a press bender which if done correctly can still produce nice bends. i would ask to take a look at some of their work or bends they make to be sure they look good. they should stay mostly round throughout the bend and not look crushed or smaller in the bend than the pipe which makes the restriction. every shop is different and you may need to shop around to find both the quality and price you want to pay. just so you know though, not sure what costs are these days but i had my full true duals welded up for 800 so a single system should be less than that. that's just for the pipe and welding not inc parts i bought.
 

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72 Gremlin 11.03 @ 121
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Discussion Starter · #7 ·
I found the Magnaflow Y with converters on ebay it lists it as w cali emissions for my truck to have the 3 cats. Magnaflow part # 93181 Best price I could find was 595.00 for the y pipe w cats.
i hear ya on the right kind of bends. This is drivin me nuts lots of research fo somthing that should be simple.
Is there a way I can get rid of the precats and do away with the 02 sensors going to them and have a y made and use a free flow cat after the y?
Remember I am in Ct and it must pass emissions.
Davis
 

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you won't pass withouth the precats, plus it's illegal so you will fail visual. the O2's will also have issues and throw codes. you can use O2 sims, but they don't always work the best.

you should just leave the factory setup and use high flow replacement precats on a larger dia Y-pipe. be it magnaflow or fabricated.
 

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72 Gremlin 11.03 @ 121
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Discussion Starter · #9 ·
WEll I just cleared the code...im going to see if it comes back. Talked to a mechanic at the dealer and he said the 2 pre cats are probly to tell a rick lean condition . the code most likely is refering to the big cat after the y. So if it doesnt trow a code in the next few days I plan to cut the big cat off and step up to a 3" free flow cat and full 3" exhaust...flowmaster, or Magniflow? What do you guys prefer and why?
Thanks for the help so far!
Davis
 

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Gen I FTW
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you won't pass withouth the precats, plus it's illegal so you will fail visual. the O2's will also have issues and throw codes. you can use O2 sims, but they don't always work the best.

you should just leave the factory setup and use high flow replacement precats on a larger dia Y-pipe. be it magnaflow or fabricated.
negative. i just went for emissions last week. all i have is headers, Y-pipe, and a magnaflow muffler. no cats anywhere on my setup. CT emissions has no visual inspection anymore on newer vehicles. the only thing they do is plug their scanner into your vehicles port under the steering wheel and then you're done.
 

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Gen I FTW
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how do you keep the O2 sensr from throwin a code? Mabe I need to go where you go.....
buy piping with 02 bungs welded in. then all you have to do is pop the 02 sensor in.
 

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negative. i just went for emissions last week. all i have is headers, Y-pipe, and a magnaflow muffler. no cats anywhere on my setup. CT emissions has no visual inspection anymore on newer vehicles. the only thing they do is plug their scanner into your vehicles port under the steering wheel and then you're done.
you have a completely different engine and setup. does not count. you shouldn't just remove the precats and leave all 4 O2's in the system. it's going to screw up the A/F mixtures. it's a lot different than just having 1 O2.

it doesn't hurt to have them in there. either buy the correct magnaflow Y-pipe with precats or have a shop make you one for probably less.
 

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Gen I FTW
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you have a completely different engine and setup. does not count. you shouldn't just remove the precats and leave all 4 O2's in the system. it's going to screw up the A/F mixtures. it's a lot different than just having 1 O2.

it doesn't hurt to have them in there. either buy the correct magnaflow Y-pipe with precats or have a shop make you one for probably less.
i bought the truck with the current setup. i think my truck only has 3 o2 sensors from the factory though. i believe 01 + have 4 sensors. correct me if i'm wrong. this is why i want to change my exhaust setup in the near future.
 

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Gen I FTW
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thing is, most guys on here run without any cats.
 

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yes late 00 to 01+ have 4 O2's and 3 cats(2 precat and 1 downstream). i don't know many 4.7's running no cats and if they are it's not a good idea. 3rd cat removal is no problem, but the precats should remain and be replaced with high flows. i guess if you had a really clean engine it may be possible to pass the sniffer test, but i wouldn't count on it. if all they use is a scanner to read the O2's then it would probably be easier.
if you never plan on leaving CT then you could maybe at least pass for there, but not many other places. most do a visual along with the emissions testing, or just a visual + safety inspection and you won't pass.

it's not that hard to pop in a couple high flows though just to be safe.
 

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Too close for missles!
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I've heard that its no big deal to remove your precats, but you really should always keep your downstream one. When I have my y-pipe replaced in the future, do you guys recomend I just get rid of the precats? or replace them all with high flows?
 

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Gen I FTW
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yes late 00 to 01+ have 4 O2's and 3 cats(2 precat and 1 downstream). i don't know many 4.7's running no cats and if they are it's not a good idea. 3rd cat removal is no problem, but the precats should remain and be replaced with high flows. i guess if you had a really clean engine it may be possible to pass the sniffer test, but i wouldn't count on it. if all they use is a scanner to read the O2's then it would probably be easier.
if you never plan on leaving CT then you could maybe at least pass for there, but not many other places. most do a visual along with the emissions testing, or just a visual + safety inspection and you won't pass.

it's not that hard to pop in a couple high flows though just to be safe.
i don't plan on leaving CT, but like i said all newer vehicles (i don't know the cutoff year), they only plug their scanner in the module below the steering wheel, let it sit for a few minutes, and you're done.
 
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