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Unread 07-10-2011, 01:48 PM   #1
digs71
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YJ 4.2 Exhaust question

I recently purchased an 87 YJ. The jeep was totally redone minus the exhaust. This is the only thing that needs work. I have found a leak in the muffler itself, and the cat is rough shape. My question is what exhaust system (Cat-back) is out there for the YJ with a 4.2? I want something that has a good tone to it, but not obnoxious. Any help would be greatly appreciated.

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Unread 07-10-2011, 01:54 PM   #2
ThomasYJ
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i would think that anything for the 4.0 would work. i dont believe you'll come up with very much if you try to do a strict '4.2 exhuast' search it's all pretty universal; only difference would be pipe diameters maybe. but to answer your question, i would look into a magnaflow cat (theyre cheap ~$100 and are better than stock) and maybe a banks muffler. deep and throaty but not loud like a flowmaster 40/44.
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Unread 07-10-2011, 02:04 PM   #3
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http://youtu.be/9sXmYI5G8Uk
or
http://youtu.be/w-XcvnrG8mQ

vs
http://youtu.be/fVhbYKhIUPQ
http://youtu.be/czZ2SzoEZhE
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Unread 07-10-2011, 02:33 PM   #4
digs71
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I love the sound of Flowmaster's. I guess if I went that route I would have to get the cat and muffler, and have someone do the pipe work from the manifold back. But for whats its worth after looking at those links check this out! Its a 4.2 with true duels (Headman headers) and a super 40

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Unread 07-10-2011, 02:50 PM   #5
ThomasYJ
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im a big fan of the flomasters as well. and i know what you mean about feeling the need to go the extra step, ive got a JBA header waiting to go in and ill be having a shop fab up the mid and tail pipe fairly soon. when you said not obnoxious though, i misunderstood and thought maybe you didnt like that sound, as ive often seen them labeled that way. guess some ppl just dont know what sounds good!!

as for the vid, thats pretty sweet!
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Unread 07-10-2011, 02:57 PM   #6
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I forgot to ask. Does anyone know the exhaust size for a stock 4.2?
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Unread 07-10-2011, 02:58 PM   #7
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and when I said obnoxious i meant i didnt want it to sound like a weed eater. I want people to turn their head and say "did you put a v8 in that"?
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Unread 07-10-2011, 04:07 PM   #8
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That is what people have said with my generic cat and flowmaster muffler. It sounds sweet
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Unread 08-17-2011, 06:02 AM   #9
digs71
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finished!

Well I got the YJ back from the shop last week. I decided to go with a custom exhaust set up from my local shop. They did a full 2-1/2 from the headers back. Went with a magnaflow cat, and a flowmaster 40 series, all were 2-1/2 in 2-1/2 out. This thing sounds amazing! Ill post a video here shortly, let me know what you guys think!
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Unread 08-23-2011, 09:46 PM   #10
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Quote:
Originally Posted by digs71 View Post
Well I got the YJ back from the shop last week. I decided to go with a custom exhaust set up from my local shop. They did a full 2-1/2 from the headers back. Went with a magnaflow cat, and a flowmaster 40 series, all were 2-1/2 in 2-1/2 out. This thing sounds amazing! Ill post a video here shortly, let me know what you guys think!
Hey man! i dont know if anyone else is following this, but i sure am! So hurry up and get that vid up! its pretty much exactly what im looking at so im pumped to see/hear this!

~Tyler
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Unread 08-24-2011, 04:07 AM   #11
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Will do, Ill have something up by this afternoon!
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Unread 08-24-2011, 11:21 AM   #12
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img_4372.jpg

img_4373.jpg

img_4374.jpg

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Unread 08-24-2011, 12:28 PM   #13
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Quote:
Originally Posted by digs71 View Post
check this out! Its a 4.2 with true duels (Headman headers) and a super 40
How can you do "true duals" on an in line motor?
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Unread 08-24-2011, 01:15 PM   #14
wanabejeeper
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split manifold, 3 exhaust ports to each down tube
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Unread 08-24-2011, 01:26 PM   #15
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Quote:
Originally Posted by wanabejeeper View Post
split manifold, 3 exhaust ports to each down tube
Hmm, seems kind of silly on an engine that needs a fair amount of backpressure to even keep it's low end power (which is what we mostly use it for). But I guess I can see how that could be done.

What would be the advantage to that over headders with bigger pipes?
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