I have a 2004 peterbilt 330 with a cat engine - 220hp

Tiny
04PETE330
  • MEMBER
  • 2004 ALL OTHER MAKES RECREATIONAL VEHICLES
  • 165,000 MILES
I have a 04 peterbilt 330 with a single exhaust pipe under the truck. I would like to remove the muffler and install 2 stacks with mufflers in the stacks (quiet mufflers). I was told that I have to use the existing muffler because it acts like a catalytic converter?
Wednesday, July 11th, 2012 AT 2:13 AM

8 Replies

Tiny
04PETE330
  • MEMBER
  • 5 POSTS
Waiting
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Wednesday, July 11th, 2012 AT 2:14 AM
Tiny
ASEMASTER6371
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Thats correct. My other concern is what motor are you running? Is it single or dual turbo? Back pressure is critical with turbo operation.

Roy
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Wednesday, July 11th, 2012 AT 2:19 AM
Tiny
04PETE330
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  • 5 POSTS
A single turbo, it only has 220hp. Thought maybe the stack, quiet mufflers would have just enough back pressure. The oem muffler sits to far back to bend a pipe back to the cab, any recommendations?
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Wednesday, July 11th, 2012 AT 3:07 AM
Tiny
ASEMASTER6371
  • MECHANIC
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To be honest, leave it stock as your motor is tuned to the exhaust.

Roy
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Wednesday, July 11th, 2012 AT 3:11 AM
Tiny
04PETE330
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  • 5 POSTS
Not what I wanted to hear :( but truth be known, your probably right. I thought it would help out on mpg
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Wednesday, July 11th, 2012 AT 3:14 AM
Tiny
ASEMASTER6371
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I bet you are running about 7 or so. Thats about the best I have heard on those. If you change the exhaust, the intakes must be changes to make it breathe better. Then you need to go into the pcm and change the horse power ratings, max rpm and in the ned you may, just may, get 1 or 2 miles per gallon increase.

Roy
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Wednesday, July 11th, 2012 AT 3:18 AM
Tiny
04PETE330
  • MEMBER
  • 5 POSTS
You hit the nail right on the head, 7 is about what i'm getting. Now, I have 5" y-pipe, elbows, stacks, quiet mufflers (slip ins) flex pipe & reducers for sale. Haha Thanks again for your help Roy.
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Wednesday, July 11th, 2012 AT 3:41 AM
Tiny
ASEMASTER6371
  • MECHANIC
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No problem, good luck
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Wednesday, July 11th, 2012 AT 1:50 PM

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