Intake/Exhaust = Mileage?

I've got an 03 Yukon with the 4.8 engine. I'm looking into getting the Volant Cold Air intake and then maybe a Flowmaster or a Borla exhaust. For those that has done these mods, did you notice an increase in your gas mileage or does it actually suck after the mods.

I can live with the noise these mods generate, but I'd hate to have a decrease in gas mileage. I usually do most of my Yukon driving on the freeway on the weekends.

What do you guys say?

In essence the less restriction there is in getting the air in and the exhaust out the better. Cooler air is denser air which burns more fuel producing more power meaning less throttle so less fuel used.
All of this said, the problem is not using that extra power. That Flow Master setup sounds so good, it's hard not getting on it, which of course translates into more fuel burned. To do all these mods and drive like your grandmother is not going to happen.
If you’re worried about fuel mileage leave it alone. The engineers at GM for better or worse worked very hard at getting the best car they could with the restrictions they had. In any case, even if you did drive like your grandmother you would never save enough to pay for the mods.
So what the hell, do it because you like it. Make some noise, impress the girls, give up steak, bologna isn't all that bad when you get use to it.
94

Thanks for the info!
I just got to reading that some of these mods only helped in the higher RPM's and actually didn't do much except increase fuel comsumption at lower RPM's...

Thanks for the info!
I just got to reading that some of these mods only helped in the higher RPM's and actually didn't do much except increase fuel comsumption at lower RPM's...

I've had my volant intake on for about 2 months now on my 04 Denali. I do almost all city driving and the fuel consumption hasn't changed driving in the city. I do feel there is more power at the low to mid range. I have 22's on and take off is a little quicker. The engine noise is pretty much the same except when you hit the 2000 to 3000 rpm range then you really hear the volant sucking more air into the engine.

This past weekend I took a trip to Yosemite and I did notice an increase in gas mileage. I drove a little over 225 miles on a little over half a tank of gas averaging about 75 mph on the freeway. That's the best I've ever gotten on my Denali. I think the increased air flow benefits MPG at freeway speeds and not higher rpms. At 75 mph my Denali tachs about 2000 rpms.

I just purchased the Corsa touring system and will hopefully have that installed this weekend. With better intake and exhaust you should definately improve your MPG at freeway speeds. You just can't put your foot into it driving around town just to hear the intake or exhaust.

I know your post was regarding intake/exhaust, but you might want to consider this--for roughly $100 more than the combined cost of purchasing and installing a CAI and exhaust, you can get a Westers PCM w/ 3D-mapping option...this will help give you more power across the band than a combo intake/exhaust will give you, and also offer an improvement in fuel economy (assuming you don't lead-foot your truck upon finding out what the Westers PCM can offer). Yes, the Westers will run you $500+ but it gives you the best bang-for-the-buck return in performance gains.

Thanks!
I'm pretty much done with the lead foot to hear the intake/exhaust so the gas problem shouldn't be an issue for me, but I know I'll do it a few times...... My Yukon is pretty much a freeway car and would just like to improve performance and especially gas mileage. As long as these mods won't actually hurt mileage I may do them over the Summer.
Any cons in using the PCM? I'm not too familiar with them.... Happen to have a link that's like a PCM for dummies? I've not a clue.....

Thanks!
I'm pretty much done with the lead foot to hear the intake/exhaust so the gas problem shouldn't be an issue for me, but I know I'll do it a few times...... My Yukon is pretty much a freeway car and would just like to improve performance and especially gas mileage. As long as these mods won't actually hurt mileage I may do them over the Summer.
Any cons in using the PCM? I'm not too familiar with them.... Happen to have a link that's like a PCM for dummies? I've not a clue.....
You can Google Westers, Nelsons, or PCMforless--they are the three main PCM aftermarket tuners for the NBS GM trucks/SUVs. An aftermarket-tuned PCM essentially replaces your existing PCM; in addition to still retaining many of the necessary factory parameters, it can be programmed to modify some of the more "fun" performance-related parameters like shift points, top-speed govenor, redline, tire size, shift firmness, fuel tables, etc. The only two "cons" that people were concerned about were that the dealer might detect it if a warranty issue arose (not an issue if you're out of warranty, of course), and smog testing. For the former--many people have noted that not even the average factory service tech can even detect a modified PCM tune; as far as smog tests are concerned--many folks have claimed that their vehicles still passed smog w/ flying colors even w/ a modified PCM.

Hi Joel, for what it is worth...
There is only one efficient fuel to air ratio. Just one.
So the key to your gas mileage is your foot.
If you want to burn more fuel, you will have to get more air. Cold air intake, free flow exhaust = a little more air. Supercharger = a lot more air.
The advantage of the 4.8 liter engine is fuel economy. Smaller engine, longer gears = less power, less fuel burnt, more economy.
So, if you stomp on it, then the air intake and free flow muffler will allow you to burn more fuel.
Other than that, you will not use the 10 or 15 more horsepowers this will give you under full throttle.

Take care, Eggert :bananasmi