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Discussion Starter #1
Hey everyone, I am going to be putting a Flowmaster 40 on my WJ, I was just wondering if anyone had the measurements of the stock muffler? The stock exhaust is 2.25'' correct? Sorry for being so lazy, its Friday and I am stuck at work, any information would be greatly appreciated.
 

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2.5" i think...research, it's a common subject
 

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It's 2 1/4 for the 5.2L. Don't go bigger than 2 1/2 though
 

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Kolak and Kevin recommend 3 inch for the V8 and 2.5 inch for the 4.0L
 

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I personally don't think the 5.2l blows enough exhaust to have a 3". This is my opinion. I am making $0 from this statement.
I now have a 5.7l Vortec in my Suburban and I stayed with the stock 3". Remember, read what I have posted in the past on this subject.
 

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On the 4.7 WJ, the stock muffler is 2.25" in and 2.50" out. You didn't specify if you have the 4.7 or 4.0. An effective exhaust mod on the 4.7 WJ is a 2.5" Carsound cat, and elimination of the 2.25" restriction between cat and muffler. Add a 2.5" muffler of your choice. I like the Flowmaster 70 on my 01 4.7 WJ; not too loud, not too timid - it's just right.

I'm running the FM Super 40 on my 5.2 ZJ - it sounds good, but it would perhaps be a little loud for everyday use.
 

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Discussion Starter #7
Thanks for the replies everyone, I have the 4.7. I have a high-flow cat already now I just need to decide if I want the 40 or the 70, decisions decisions.
 

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So split the difference and get the 50SUV - I think the 3-chamber Flowmasters (50, 70) have a better overall sound quality than the 40 series (two chamber). I'm running the 50 SUV on my 4.0 MJ, and I am considering replacing the Super 40 on my 5.2 ZJ with one.
 

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peltandra said:
So split the difference and get the 50SUV - I think the 3-chamber Flowmasters (50, 70) have a better overall sound quality than the 40 series (two chamber). I'm running the 50 SUV on my 4.0 MJ, and I am considering replacing the Super 40 on my 5.2 ZJ with one.
70 series is a two chamber too just longer.
 

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Save money and go with straight pipe from the factory CAT to the back.

Not much louder then the FM40, which I had for a while.
 

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xtianknight said:
peltandra said:
So split the difference and get the 50SUV - I think the 3-chamber Flowmasters (50, 70) have a better overall sound quality than the 40 series (two chamber). I'm running the 50 SUV on my 4.0 MJ, and I am considering replacing the Super 40 on my 5.2 ZJ with one.
70 series is a two chamber too just longer.
You are incorrect.

www.flowmastermufflers.com/mufflers.html

scroll to bottom of page for description of FM70 which clearly specifies that it is a 3-chamber design.
 

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Discussion Starter #12
JohnBoulderCO said:
Save money and go with straight pipe from the factory CAT to the back.

Not much louder then the FM40, which I had for a while.
I would LOVE to go with a straight pipe cat-back, but I doubt that my Jeep would pass emissions. I had a straight pipe on my 88 XJ from the cat back and loved the sound, luckily I knew someone who would pass me, unfortunately dont live in that state anymore. 40 series here I come.
 

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Muffler has no affect on emissions, only sound. Depends on the state if you need the muffler. You need the CAT for emissions.
 

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I run a flow 40 on my 4.0 and have gotten used to it for everyday driving but my neighbors are still not used to it. :lol:
 

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peltandra said:
xtianknight said:
peltandra said:
So split the difference and get the 50SUV - I think the 3-chamber Flowmasters (50, 70) have a better overall sound quality than the 40 series (two chamber). I'm running the 50 SUV on my 4.0 MJ, and I am considering replacing the Super 40 on my 5.2 ZJ with one.
70 series is a two chamber too just longer.
You are incorrect.

www.flowmastermufflers.com/mufflers.html

scroll to bottom of page for description of FM70 which clearly specifies that it is a 3-chamber design.
Opps! You're right
 

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JohnBoulderCO said:
Muffler has no affect on emissions, only sound. Depends on the state if you need the muffler. You need the CAT for emissions.
Does the exhaust stay longer in CAT because of the muffler? Thus, passing smog better?
 

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the 4.7 has a 2 and quarter into the muffler stock, you'll tell a difference with a 40 series and 2 and half inches at least cat back. the 50 series has a more mellow sound, i dont like it as well at the 40 but both are nice
 

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I bought a 3in exhaust from Kevin 3in cat, 3in muffler(70) tailpipe is of course 3in. The guys at the muffler shop had a hell of a time squeezing it in there but after a couple of trips back for adjustments it seems to running without rattling. CarX is awesome for exhaust, I bet I paid about $65 for over 3 hours of labor. I have the 70 series muffler and sound is nearly perfect.
 

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i have kolak's system and it is awesome it sounds like a v8 should i think a 40 series would be way to loud i would get the system from either KOR(which is kolak's system) or directly from kolak here is a like to kevins site http://www.kevinsoffroad.com/exhaust.html and a link to send kolak an email mailto:[email protected]
 

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I personally don't think the 5.2l blows enough exhaust to have a 3". This is my opinion. I am making $0 from this statement.
I now have a 5.7l Vortec in my Suburban and I stayed with the stock 3". Remember, read what I have posted in the past on this subject.
My 5.2 v8 93 limited grand Cherokee blows over 100 db stock exahust but im probly going to cut pipe out and add the flow key fob pack to mak it 200db and gain 15 hp
 
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