6.o exhausts
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by neb44
Does it hurt anything to cut off the cat and muffler on a 2004 6.0 and replace it with a straight pipe?
This thread will start WWIII fairly soon, so put the plates in your armor and the mag in your rifle
Senior User
Joined: Sep 2004
Posts: 235
Likes: 0
From: S.W. Michigan
Well, i don't know about the cat (nor care to comment 
), but I had the muffler cut out and a piece of pipe bent and welded into its place. Did I see any gains in HP or MPG? Not tons, but I did notice better throttle responce and a bit louder turbo whistle that I love. I just can't get myself to loose the cat (not until 100,000 miles anyway)
The cat knocks down alot of the noise. With out the muffler it still sounds the same as it did when it was stock until over 2200 rpm and into the throttle a bit. Then she starts to bark abit, but not obnoxious at all. My buddy said it had a nice throaty rumble when i pulled away from his house.
I do notice some resonance at 2000 rpm on the freeway. But it does not bother me. I logged 247,000 original miles on my 1992 F150 302 manual, 100,000 of those with out a cat or muffler, so i am used to some rumble on the e-way.
The muffler delete ran me $50 at the local muffler shop.
), but I had the muffler cut out and a piece of pipe bent and welded into its place. Did I see any gains in HP or MPG? Not tons, but I did notice better throttle responce and a bit louder turbo whistle that I love. I just can't get myself to loose the cat (not until 100,000 miles anyway)The cat knocks down alot of the noise. With out the muffler it still sounds the same as it did when it was stock until over 2200 rpm and into the throttle a bit. Then she starts to bark abit, but not obnoxious at all. My buddy said it had a nice throaty rumble when i pulled away from his house.
I do notice some resonance at 2000 rpm on the freeway. But it does not bother me. I logged 247,000 original miles on my 1992 F150 302 manual, 100,000 of those with out a cat or muffler, so i am used to some rumble on the e-way.
The muffler delete ran me $50 at the local muffler shop.
New User
Joined: Jan 2004
Posts: 12
Likes: 0
I did a turbo back kit on mine with cat off at first, unless you want your truck to sound LITERALLY like a jet engine no kidding here you almost need ear plugs with windows down. Leave the cat, you'll burn cleaner and not disturb critters for miles around, also I did not feel any difference in power going cat to catless.
Senior User
Joined: Apr 2004
Posts: 181
Likes: 0
From: Florida
laredo7mma, I am curious about the straight pipe you had made. A local muffler shop had 3.5 inch pipe and the equipment to bend it? I haven't looked into this locally and have been to quite a few muffler shops but I don't believe any I have been to have had the materials or capability to accomplish this. (Not doubting your experience at all by the way) Was this a chain type like Midas or something only local to you?
Senior User
Joined: Sep 2004
Posts: 235
Likes: 0
From: S.W. Michigan
kb1aah - You are correct. They bent and expanded the ends on a 3.0 inch piece of pipe. The guy who owned the shop was getting ready to buy the dies required to bend larger pipe but has not sprung for them yet.
I figured even with a 3.0 diameter pipe in there it has to still be better flowing than the stock muffler. Some day when a get a few extra bucks I will get a SS cat back system. Need the SS here in MI, just got our first snow today, only 8 inches and more to come. Gotta love it.
I figured even with a 3.0 diameter pipe in there it has to still be better flowing than the stock muffler. Some day when a get a few extra bucks I will get a SS cat back system. Need the SS here in MI, just got our first snow today, only 8 inches and more to come. Gotta love it.
