01 2500hd gas mileage

I thinking about changing my air intake and exhaust on my 01 2500hd w/6.0l engine.  I am wondering if anybody that has done this can tell me if they got any better gas mileage from it.  I fully expect the truck to run much better, I am just curious about the mpg's as a bonus.  

If you REALLY want it to run better and get better MPG, stop using 87 octane. Use at least 89 and you will see a increase and power and MPG over time more than you will get with a air cleaner kit and exhaust. The reality that your engine was pretty well tuned for factory on intake and exhaust if it was that easy to get power and MPG gain (given the pressure Detroit has been under in past in HP and MPG wars) they would come that way. This is not a 75 chevy with 8 to 1 compression and no tuning on intake and exhaust.  

I have been running 89 and my truck does run a little better (no knocking sound).  However the truck still seems like it is not running at its full potential, but that is why I am asking the question.  I am just curious if it could run better.  

What is you current configuration?  (tires, lift, axle ratio and such)  

I currently have 265/75/16 AT tires, 4:10 rear end and everything else is stock.  

Well though some may disagree, a air cleaner is not going to improve MPG. THis myth started in carb days were a different air cleaner could slightly lean carb out a bit do to slightly less pressure drop relative to static pressure but air cleaners have improved since then and FI is mixture controlled regardless of air cleaner too. YOu could change O2 sensor as they tend to go a bit rich with age and new one can sometime perk it up a bit and improve MPG in process too. (change primary ones near engine, do not worry about ones near CAT's because they have no effect on mixture) On exhaust, sometimes it can gain you some top end and sound but it can detract form bottom end and MPG (especially in town) because at low and middle RPM engine actually like a little back pressure for best response. That and even exhaust is better tuned today than in past years. You could invest in a aftermarket tune as that can usually pick up some ponies but you need to run 89 or better octane all the time to benefit the most from such a tune.  

Thanks for the advice.