Cut muffler off (straight pipe) information - Ford Powerstroke Diesel Forum
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Old 06-02-2010, 06:18 AM
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Cut muffler off (straight pipe) information

I had my muffler cut off today. I didn't have any other soot collectors or cats on it. Downpipe is 3" which comes into a 3.5". Here's my observations for other folks...

Truck info
7.3 (duh) with no mods other than what is in the signature and the exhaust is all factory. No chip, tuners or programmers (that I know of).

Sound
At first I couldn't hear anything different until I pulled out of the garage next to a barrier wall. Turbo whistle was unreal and there was definitely a louder rumble when you gave it gas. Idle wasn't much changed from what I could tell.

EGT
100*F drop in my EGT's. I know in certain areas I would run about 800, now it is at 700*. They also come down alot faster. It will go from 1000 to 600 in about 3 to 5 seconds compared to 6 to 10 before. When pulling into the driveway and letting it cool down it would normally take it about 35 to 40 seconds to go from 600 down to 400. Now it's about 15 seconds.

Horsepower/Torque
No noticeable difference

Boost
Normally I'd see it flicker between 17 and 19 PSI. Now it runs 21-23 PSI.
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Old 06-02-2010, 07:07 AM
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wish I would see those bost #'s but i guess being at about 8500ft would do that lol
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Old 06-02-2010, 07:13 AM
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I did the same thing, well I got a 2003 6.0 however my cat is still under there. I have been thinking about cutting it out. I know with just the striaght pipe in place of the muffler it sounds way better. I dont' have a boost gauge... I think I will get one of those soon. Would removing the cat really help it? I don't have emissions testing down here in South Texas, however I don't know how really hard they visually inspect a truck here? I just moved from Louisiana. Any thoughts ideas?
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Old 06-02-2010, 10:45 AM
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Anything that'll help it breathe I'd say would help out so removing the cat would. Some options I've seen for the cats if they do visual inspection is folks will cut it open, gut it out then re-weld it back up so it's just like it's open.
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Old 06-02-2010, 10:50 AM
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Quote:
Originally Posted by craftkr View Post
I did the same thing, well I got a 2003 6.0 however my cat is still under there. I have been thinking about cutting it out. I know with just the striaght pipe in place of the muffler it sounds way better. I dont' have a boost gauge... I think I will get one of those soon. Would removing the cat really help it? I don't have emissions testing down here in South Texas, however I don't know how really hard they visually inspect a truck here? I just moved from Louisiana. Any thoughts ideas?
I run my truck with no Cat or Muffler but Im from Indiana, where they have no emissions for diesels.... Sound is unreal.. I love it.

I have some videos on youtube I can send ya.
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Old 06-02-2010, 10:57 AM
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So am I correct that there is a PDF and a Cat on an 2003 F 250? I thought all I had was the cat, but I forgot about the PDF thingamajigy.... Man diesels have gotten way complicated compared to my older ones...
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Old 06-02-2010, 11:35 AM
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late model 99 7.3, i cut my pipe within 24hrs of purchasing the truck. it definatly does wonder for the truck all around.. now ive saved and did a 4 and 4 inch exhaust. and made it run even better, its amazing how much exhaust flow effects it. and yes sound it beautiful.
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Old 06-02-2010, 07:43 PM
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Some folks say that they did a 4" and didn't make much difference from just cutting off the muffler?
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Old 06-02-2010, 08:30 PM
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Quote:
Originally Posted by merc123 View Post
Some folks say that they did a 4" and didn't make much difference from just cutting off the muffler?
very true..a slight drop in egts..

if you striaght pipe the stock exhaust your good for like 400hp i believe..i went with the 5" mbrp kit jsut for the sake of the noise haha..i see 30psi chipped..and run at about 650-700 at 75mph
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Old 06-03-2010, 04:44 AM
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I don't have emissions testing down here in South Texas, however I don't know how really hard they visually inspect a truck here?

Just had my inspection done in Central Tx and there is no emission testing on diesel just gassers
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