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Old 08-15-2012, 06:58 PM
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anyone with a 2.5 straight piped?

i was planning to take off my stock cat on 94 2.5 to gut it out, but it is rusted to shit and i dont want to take it down and not be able to get it back up, i was thinking about chopping the exhaust off at the header(around downpipe) and welding a straight pipe to an autozone muffler. anyone done this or have any input?

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Old 08-15-2012, 08:17 PM   #2
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Nobody on this forum has done it, as it is a Federal Crime to remove Federally Mandated emissions equipment, not to mention it's highly frowned upon here

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Old 08-15-2012, 08:22 PM   #3
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Xpress is correct. I did not do mine today.
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Old 08-15-2012, 08:22 PM   #4
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Originally Posted by jerseYJ View Post
i was planning to take off my stock cat on 94 2.5 to gut it out, but it is rusted to shit and i dont want to take it down and not be able to get it back up, i was thinking about chopping the exhaust off at the header(around downpipe) and welding a straight pipe to an autozone muffler. anyone done this or have any input?
Taking the CAT down is pretty easy and you shouldn't have too hard of a time putting it back up though, it basically just floats there bolted in by two flanges if I recall, has a heat shield around it too. Soak the bolts for a couple days with some PB Blaster or Aero-Kroil. I think you should at least attempt it first before you spend all that time fabricating and welding something up, the CAT is an important part in the exhaust system.

Also, I don't know if your Jeep is your DD, but it is not legal to do this in NJ, you wont pass a state inspection. When I replaced my CAT I just wanted to see how loud it was just with the straight pipe, trust me, it's freaking loud and annoying, even for the 4-Cylinder. You could attract attention from the local police too. Just a suggestion.
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Old 08-15-2012, 09:21 PM   #5
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Yup...

but, one thing to consider is that your back pressure will change requiring more fuel to match the flow. Ideally, you want more intake with the less restrictive exhaust, and more fuel. To get ideal mixture you would need larger fuel injectors, remap your computer, and possibly even a larger intake and plenum.

granted this is under "ideal" design; what you propose is possible, but if that is all you do you can end up with pre-ignition problems or "knocking" and performance will suffer.

Oh, and typically, to take advantage of an open system like that, it would need to be rev'ed up quite a bit. So in a way, racing is basically the only way to take advantage of that type of system.
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Old 08-15-2012, 09:52 PM
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thanks for insightful input everyone. i think i will just try to soak it in pb and see how it goes. i haven't had a cat on a car since...this jeep hahaha. my altima and 240 was straight pipe from header back and the latter was probably the loudest car i know locally lol. ive been looking for a test pipe but cant find one for a jeep, are they interchangable with any other vehicles? cops and inspections?...
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Old 08-15-2012, 10:13 PM   #7
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thanks for insightful input everyone. i think i will just try to soak it in pb and see how it goes. i haven't had a cat on a car since...this jeep hahaha. my altima and 240 was straight pipe from header back and the latter was probably the loudest car i know locally lol. ive been looking for a test pipe but cant find one for a jeep, are they interchangable with any other vehicles? cops and inspections?...

lmfao....this is a jeep i kno how you feel all my other cars including the 240 :,( was straight piped but trust me just keep it stocl or at least a high flow cat it wouldnt soumd right with anything else and i wish it would but you kno how the cops get
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Old 08-15-2012, 10:41 PM   #8
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All you need to know is the pipe size, and any chunk of exhaust pipe becomes a "test pipe".
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Old 08-15-2012, 10:57 PM   #9
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mine has a borla stainless header that goes straight to a muffler with no CAT (previous owners work)... not sure brand of muffler though
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Old 08-15-2012, 10:59 PM   #10
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sorry - wouldn't let me edit ... mine has a borla stainless header that goes stainless straight to a muffler (also borla i think) with no CAT (previous owners work)...
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Old 08-15-2012, 11:42 PM
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All you need to know is the pipe size, and any chunk of exhaust pipe becomes a "test pipe".

yea of course but then gotta make flanges and over that id rather just replace the whole exhaust. but i think ill just gut the cat, hopefully tmrw

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sorry - wouldn't let me edit ... mine has a borla stainless header that goes stainless straight to a muffler (also borla i think) with no CAT (previous owners work)...
lucky dawg you.
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Old 08-16-2012, 12:33 AM   #12
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yeah and luckily in am in the city and they emissions test, but only 95 and up !!! winner winner chicken dinner ! (got an 88)
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Old 08-16-2012, 06:30 AM   #13
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I have a 93 with no cat and mine drives great and sounds great. I also live in South Carolina so there is no emission tests here. Pretty much any car or truck here looses their cats.
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Old 08-16-2012, 08:01 AM   #14
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