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Discussion Starter · #1 ·
Hey guys.
My truck is a full time trailer hauler. I use it to haul horse trailers for featherlight and trailswest.
this truck gets 12,000 miles a month put on it.
it's 100% stock right now and i really need to milk some more MPG out of it.
I"m just getting started doing this for a living so I don't have tons of cash to start out with. So i need to do this little by little.

I have a drop in K&N i put in yesterday because my paper one was clogged and i figured it will help a little.

I was looking at those true flow sealed air box cold air intakes. But i got to thinking do they really flow that much better then the OEM intake tubing?
because all they are is a drop in filter and new airbox to intake tubing.

Also I was thinking about cutting the muffler off. this will help millage right? and also lower my EGT's?

I pull double 24 + foot trailers the ones that are half camper half horse trailer through the rocky's all the time. this truck gets worked hard.

So for starters I was thinking. remove the muffler and go cat back straight and get a cold air like the true flow.

But the biggest thing is i don't wanna mess with reliability at all.
Any input would be awesome thanks guys.
 

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Removing the stock muffler won't do a whole lot on an '05 because you still have a cat on it. I picked up a 4" down pipe to 5" system off ebay for $270. It has made quite a difference, IMO, compared to the stock exhaust. All I have is a drop in K&N also. I have heard that a cold air will make a noticable difference though.
 

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Well, from my experience, the cold air box made no difference in mileage. Neither did the 4" turbo back exhaust (the offroad system). One thing that did make a little difference was running the predator tuner. I picked up about 1-2 mpg. Granted, possibly if I could keep my foot out of it, I might have seen a little more increase from the other mods, but what is the fun in that? The k&n drop in will flow just as well as any cold air intake. Personally, I do not like the k&n since the time I pulled it out to check it and held it up to the light......you could see pinholes all throughout. In my experience though, it doesn't really matter how I drive my truck it gets pretty close to the same mileage. I know something that will help is to keep the rpms below 2000 when driving and the mileage should increase some.
 

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Put an intake on and an exhaust system as the straight pipe will be noisey in the cab. My system is pretty quiet. A small tune of 50-70 hp would help out on mileage with the intake and exhaust. Just my $.02.

Ryan
 

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I second Ryan's comment. Out of all the exhaust systems i love my silverline 4". Anything you do to make your engine breath in and out easier will improve your mileage, not dramatically, but every bit helps. But i think your best bet to see a noticeable improvement in mileage is a tuner. I am seeing anywhere between 21-23 mpg highway. When loaded down i get around 12-14.
 

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I have use true flow,so far. it is the extreme duty. It is well built, not made of plastic! as for, performqnce, it was hard to tell. I would say 5 to 10 hp. It did cause less smoke out of the exhaust pipe. Which tells me the engine is getting more air...
 

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i second what ryan said
 

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Discussion Starter · #8 ·
Thanks for all the great info guys.
It's set me on the right track.

How often do you guys change your tranny spin off filter? I've been doing it every other oil change and every 50K it gets a tranny flush.
 

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I change mine about every 7500 miles or so. Mike L. recommends to change it more often than the owner's manual states. I feel it is cheap insurance on an expensive tranny. In case you don't know, Mike L. is the resident Allison guru on most GM forums.
 

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I have a drop in K&N i put in yesterday because my paper one was clogged and i figured it will help a little. Bad idea, it just allows more dirt in, that is the only "improvement".


I pull double 24 + foot trailers the ones that are half camper half horse trailer through the rocky's all the time. this truck gets worked hard. and as a result, your IAT goes north at all times, especially when the fan engages

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But the biggest thing is i don't wanna mess with reliability at all.

Any input would be awesome thanks guys.
You should really take a look at the true CAI. Or any intake proven to reduce IAT, volant makes an effective one also, but this one looks completely stock and uses the element that has been proven most effective at filtering while not creating excess resistance. I know that when I tow in the summer in the rockies, I get around a 2 mpg increase. Partly because it helps keep my fan off, and partly because it reduces combustion charge air temperature. It results in a minimum 100 degree, often 200 degree, lower EGT as well, these things I have seen.

So, it is not about what "flows more", it is about temperature control. it has been stated that airbox temperature gets over 220 degrees in the stock settup. Then the problem worstens in the turbo...all means lower oxygen concentration and too rapid combustion, things that hurt the efficiency of the motor.

I agree that an exhaust is also a good idea for egt. I went from 8 mpg stock to 11-12 mpg, by adding the airbox, TD-EOC (airdam), and exhaust. Like 40%. And it's much quieter without that fan all the time.
 

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Discussion Starter · #11 ·
So it sounds like i need to throw that K&N away?
Dang thats 60 bucks down the pooper.
Figured with them being such a big name they must be somewhat good.
 

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Discussion Starter · #12 ·
Whats the best CAI system for under 300 bucks?
 

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i'm runnin the S&B and i love it..afe,volant and their are some others out there that are good..
 

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Whats the best CAI system for under 300 bucks?
one that gives cold air. That probably sounds flippant, but almost none of them do. Once the fan spins on, none of the so called CAI's work, they just get hot, hot, hot.

Anyone can see this for themselves, with a scanner that will allow you to watch IAT.
 

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I know this is old post but I agree with travelswithcharly. Unless you have actual tubing that is getting air from somewhere else other than inside the engine bay its not cold air. K&N I think has the cheapest claim to cold air, a metal plate in the engine bay is not cold air. I think the advantage of all these CAI is the tube that goes from the filter to the turbo. The stock app are very restrictive, they do that for noise reduction. The tube just puts the air where it needs to go. Instead of goin threw other compartments to reduce noise.
 
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