The commercial engine is 300 horse, and much more torque at a lower rpm. There is food for thought there, with the rpm raised the hp would be much higher. Sooner or later someone will start playing with the commercial ECM which goes on an engine with much less EPA regulations. Last week was looking over a 300 horse and was tempted, but the Cummins guru said "don't even think about it." Down the road bet the newer trucks will be retro fitted with the earlier engine. That is for those that want to play.

 

Anyone who cut or straight-piped your Cat...What was your MPG before and after?
I mean is it worth it?

 

I had a post about the gutting of my CAT, it got shut down by Jack so i am sure this one might be soon. Anyway, I noticed an increase in repsonse and after a few weeks of driving a solid inc of 1.5 mpg. Then I put the Donaldson muffler on and noticed no inc in mileage but it was a little better on turbo spool up. Wasit worth it, to me yes. I will put close to 80,000 miles on my truck this year, that extra 1.5 mpg will add up. I live in Kansas though, we don't get tested so odds of me getting caught are slim to none.

Now that being said, I have just over 10,000 miles. I truly believe you need to put some miles on your truck. I can't give you a real good ex., but my last tank of empty driving before my last trip was a little over 16. I am now at 18.2 hand calculated. Had a 1000 mile trip with 9,000lbs behind me, between the 2 tanks of empty driving. This could very well be the stations switching from winter to summer fuel, don't know. All I know is my truck started at 11.5 mpg and is up to over 18.

Also, from this post and the thread i started I am appantly the only one the noticed anythin when doing this. And no iam not one ofthose guys talking up their mileage. i was just as ****** as the rest of the people out there when I was getting crappy mileage

 

My truck when it was new, got 17 on the highway with no load going from New Orleans and back once each two weeks. It was 235 horse, 4wd, five speed, limited slip 354.

 

Most of the pre 600 engines did, i'm referring to the 600. I have only seen a few getting decent mileage from the get go and they are mostly 2wd trucks

 

I think you missed the point. 17 is nothing to brag about for all highway, no stop and go, just empty cruise. Bet the 600's are doing just about as good. Of course stop and go brings it down even more. This was also with 15,000 and better on the truck. While the truck was doing this, I heard all the claims of 21 and 22. In the long run after broken well I bet it's not so bad with the 600 trucks.

 

Do these new trucks have O2 sensors? If they don't then the truck will never know you remove it. And if the truck doesn't know...

 

Nope, no sensor

 

Since removing the cat is a violation of federal law, I'm closing this thread, just like the last one. People with a decent post count should know better.