5.9 or 6.7
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Joined: Jan 2009
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From: Arizona - The Photo Radar Rip-off State
Performance - 6.7
Reliability and mileage - 5.9
If you do the deletes the 6.7 would be awesome, but no warranty and you have to worry about the EPA Gestapo. I've owned both, and I sold the 6.7 and kept my 5.9. It does everything I want it to do, and I pull a lot of heavy loads.
Reliability and mileage - 5.9
If you do the deletes the 6.7 would be awesome, but no warranty and you have to worry about the EPA Gestapo. I've owned both, and I sold the 6.7 and kept my 5.9. It does everything I want it to do, and I pull a lot of heavy loads.
You could not give me a NEW 6.7 
Big Joke just my 2cents
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Joined: Oct 2007
Posts: 1,801
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From: Saskaberia, SK
I had a 2000 5.9 and moved up to the 6.7. Once the engine can breath, its a whole new animal. I will have to vote for the 6.7. Its quiet and smooth, the 6 speed auto with engine brake is amazing.
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Joined: Jun 2005
Posts: 781
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From: Colorado Springs, CO
everyone that i know that hauls with the 6.7.. has had there exhuast brake stick on them... and its expensive fix because some of them had it stick and melt the #1 piston..
another wierd issue is they have a 3rd and 4th injection per cycle for emissions and compression knock control.... and because of this the injectors see alot more use compared to the 5.9
another wierd issue is they have a 3rd and 4th injection per cycle for emissions and compression knock control.... and because of this the injectors see alot more use compared to the 5.9
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From: Home: Kaplan, LA - Pipelining In: Pecos, Tx
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I could not get use to the Trans and the Motor. Stock I could see EGTs through the roof when in Regen and it was in all the time! Then I did all the deletes and that helped the EGTs but the truck ran Strange. I had the Smarty on it everything was ok But when you got on it the turbo acted real strange as well. I got spanked so my times in it I hated to even bring it out!
I am a 5.9 Guy and thats my thing, not the 6.7 turds
I am a 5.9 Guy and thats my thing, not the 6.7 turds
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Joined: Jun 2005
Posts: 781
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From: Colorado Springs, CO
there good motors.. just the exhaust brake tends to stick up and melt piston #1 just fyi... i have over 30 friends that have melted piston #1 while towing and using the exhaust brake...
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Joined: Dec 2009
Posts: 109
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From: Marietta OH IO
I loved my 6.7 with the EB and auto. However i just got me a 5.9 with the 6spd and seem to like it a little more so far. Mileage is better on the 5.9 but i also had a level kit which hurts the mileage on the 6.7. I NEVER had my 6.7 do a regen and the power of it was great. So i can not say anything bad about it.