I had no issues pulling what ever I wanted with stock 3.73's and 37's... I did 4.30's because I thought it would be some amazing change... Its just annoying.

 

good word of advice Country429, CSIPSD has been there done that, i swear the guy knows everything to know about these trucks, i'd just take his word for it, i have and it hasn't done me wrong

 

A friend of mine put 4.56 in a 05 superduty with a 6.0 with a set of 37's under it and it does well. My other concern is egt's at highway speeds. Are they going to be really high turning that kinda rPm. Now with 3.73's pulling a 25 foot gooseneck with four Polaris rzrs on it it's all I can do to run 70 mph and the egts run from 1000 degees to 1200 and sometimes will alittle higher for a seccond going up hills.

 

he also has another gear then you do too..

 

Higher RPM's lower EGT's... The worst thing you can do when working the truck is lug it.

That being said, high RPM's kill MPG.



Have you corrected your speedo? Or are you running 80mph when your speedo reads 70...

 

You right I forgot a about the 5 speed

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I have not corrected the speedo it is 10 off

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So 4.30 it is, That's why I come here for questions I can usually get my answer without even making a post.

 

Honestly I would not go bigger then 4.30's...

Speedo is off a percentage, as the speed goes up, the MPH differance gets larger. Changing the gears will not fix the speedo being off. You need to have the GEM module reprogramed to correct the speedo.

 

dont tell him that, it will go to his head. then he will try to make us all bow before, joe the powerstroke master.

 

Keep it up... And I wont come over this weekend and finally fix your pile.

 

all hail joe!