Trebin

I run the 87tow/performance on my 2011 kr 4x4. Lost a little mpg but enjoy the response of the engine. Wasn't what I expected but I guess I can live with it. I was told that my mileage would increase by 2 mpg

ClaySlayer

As far as 87 vs 91+ burning 91+ allows you to up the timing a little and you can get just as good MPG if not better and have even more power. Low to midrange response is better too especially under load as the engine will make better low-end power (less knock) and require less down-shifting. I'd like to know more about the EB tuning because a loss of ~4mpg is does not sound normal. Granted, most of the info you'll see will only brag on better top-end power or a smidgen better MPG which makes for better ads but doesn't really do anything for the average driver that is satisfied with their vehicle's current performance. Most of the engines I've driven/owned that were tuned didn't produce a night and day difference but if you halfway knew what was going on with your vehicle when you drive it then it was a nice improvement...such as towing a load uphill. Other than that you'll just have to drive one to understand...but if you're the type of person that isn't sure what type of engine is under their hood other than it's under there and you press the gas to go and brake to stop then a tune probably isn't going to do jack for you...not saying you're that type of person but a lot of people are and expect to feel the same feeling that strapping a blower on would then they get disappointed...they also expect a big jump in MPG and that just isn't going to happen either...1 MAYBE 2mpg is all you're going to get. And if your right foot isn't smooth on the gas you'll probably never see any gain and might actually lose some.

Cliff Notes:
We tune them because we like improving things. If you're satisfied with current performance it's useless to you.

cdvaight

I got the aFe and tunes from Mike. I know you want a difference between octanes but I can't give that. I only run 91 in my 6.2 and the difference is extremely evident. Shift points are higher, speed is greater (I hit 60-65 in 2nd WOT now), all around a completely better driving experience. I was shifting hard between 2nd and 3rd but sent Mike an email and he sent a new tune a couple days ago and it is even better without the hard shift.

cdvaight

My experience with the tune is completely the opposite. My truck did wake up, my MPG's are still bad (due to daily driving habits but knew that buying the truck and motor), I always want more power.

parkgt

Thanks for the replies. I had both a 2000 and 2003 GMC with the 5.3l that had computers tuned because that engine and 4 spd needed it. The 5.0 and 6 spd are so much better that I guess I already feel like I have stepped up a bunch.

On my late Sept build 5.0l running ethanol free 87 I don't yet feel the need for more of anything. I don't hot rod much and very seldom get above 80 mph. The heaviest trailering I will do is probably about 4,000lbs, only pulled about 2,200 so far and it was fine.

At a 1-2 mpg increase the expense of 91 octane and a tune would take a long time to payback, if it ever did. Maybe after I have had the truck a year a tune will bring back the big smile I have now every time I drive it.

grpark20

Truck in sig.....new MPG on first tank 13.04 city. 87 mileage tune 12.84 city and 87 performance tune 12.53 city. Mileage tune feels just like stock except no delay with changing gears. Performance tune is night and day and drivability is way up. Actually fun to drive with performance tune. No highway mileage test yet or towing with the towing tune. 100% happy with tunes. Truck only has 3500 miles and we are on winter blend gas. Estimating 16 highway on summer blend when truck breaks in at around 10000 miles. Can't beat free tunes and customer service from 5 star....that part is priceless to me. Soon will be towing 5000 pounds across the country (3000 miles). I'll have a good review then.