Yep, my rig (03 Yuk LX 4x4) is not exactly a performance truck or a gas sipper. However, w/ nothing more than a K&N I was able to get 19mpg on the hwy, but getting that thing up and going around town yields 12/13mpg.

So...based on my calculations, it would take 2 years at current gas prices to make up for the expense of headers. Even then...how much will headers help if they are dumping into stock catalytic converters??? I can tell you my wife won't ride in any of my cars w/o cats because of the smell, so she sure ain't going to ride in the Yuk if I go "illegal" just for economy.

I've tried the Gibson cat-back -way too loud for what this vehicle is used for. I put it on my brother's Yukon instead.

Even though its been discussed before...what are you guys doing that actually works??? The efan thing is out for me because I'll tow the 'bird from time to time and can't afford overheating. The tornado air crap or throttle body spacers have been tried w/ no benefit. Let's cut through the marketing junk and hear what works for these full size vehicles.

I didn't buy it to get 30 mpg, but we all know there's ways to improve.

Let's hear it!!!

 

LC-1 Wideband- $200

Tuning software- $600

This could bring you up to 16-18 in town.

 

now...that sounds interesting. I'll have to do the research on that.

 

I wonder if long tube headers would benefit these trucks at all for efficiency dumping into stock cats?

 

I know most people here are making their trucks fast, which most of the time leds to less mpg. But for some of us, with the price of gas, we re having to give up being fast for mpg. I would like to know too what we can do besides the "drive like a grandma" style. ( i m already doing that) And its not working. On the highway, I do pretty good but around town is killing me. I cant afford $800 bc of friggin gas being so high. SO whats some cheap things that actually work.

Do the air boxes and a K&N really benefit enough to justify $200?

 

OpenLoop SD Mode, with some creative AFR settings you can even get highway mileage into the low 20's. *cough* lean cruise *cough* (i mean setting the commanded AFR in the cruising range to 15.x not the Lean cruise settings that dont work)

 

I talked to several folks, and the consensus of the "air kit" is that it really does out perform a simple filter replacement. It comes with some different noises. If K&N can advertise 15rwhp in a cold air kit (not the polished version -pretty, but holds heat) then they have to be on to something for efficiency. I may even move to that and try it.

 

You won't see much gains out of that if any. Everything helps, but I doubt you will see much of a difference.
I vote to stay with the K&N drop in filter and get a smooth replacement air tube. There is someone that sells them. I forget who that is though. That would be the best route to take.
If you do decide to go with a complete replacement system, get one off of ebay. They seem to have them pretty cheap sometimes.

Jim

 

I believe that Air-raid or Volant sells the replacement tube only for about $100. It states that it out flows the stock plumbing by 400cfm -?

 

That's the Airaid MIT tube.
For the MPG, all you can do is lay off it.
I don't know how it is that headers are going to help your fuel economy? Anytime you modify your stock config it's to push more air and fuel through your motor. Increasing your HP by 15 (which a KN won't) isn't going to enable you to stay off the throttle any more than you would without it.
Just keep it under 75, drive around in 4th everywhere, buy the cheap 87 octane and don't ever punch it.