Well i promised a few of you guys that i would do a little first drive write up on the 4l60 to 4l80 difference. So here it is:
First off I started with the 5.3 4l60, fun to drive but boring at most times. Then I did the 6.0 4l60 and it was better but still felt sluggish at times, I decided to put in a yank tt3k stall and that woke up the truck. I was running great and well I couldn't get enough so on goes the turbo. Forget everything you have heard, nothing puts a smile on your face like FI. Started at 3.5 psi due to fuel issues and got that worked out and went to 7psi, after 2 weeks of beating on the truck just a few times and never gettting a good race the trans went. There aren't any really good comparisons here to see the difference in the two, as far as driving so I thought i'd share my opinion.

The 4l80 is heavy, if i had to guess prolly 150-200lbs more than the 60. Shift kit from transgo was fairly easy, if you can pull the trans you can install the shift kit. The actual swap on a scale of 1-10 would be 9 for the average joe(welding, cutting and measuring the x member and changing the wiring,tune). For a welder the swap would be a 5 if a segment swap was performed by a tuner.

Driving with the 80 for the first time sucked, it shifted horrible, the truck was sluggish, i really didn't beat on it the first time out cause i wanted to make sure it would be ok to go! I was logging and came back to take a look at the tune, and i realized that the trans settings were stock. So i went in for the night and had nonnie help me with some changes along with justin at blackbear performance.

After the updated tune i got the truck out and made my first real drive. It felt good but not right due to some shift points and things but better than before. I changed those things and the truck is running better. I lost a good bit down low, at a stand still the truck would blow the tires now it slowly takes off but the difference is at 3k rpm. It feels like another 5psi of boost had been added up top. Part throttle shifts are so much better than i could have ever imagined with the 60. WOT shifts are awesome, just a crisp bump and its in gear and keeps pulling with no hesitation. If the rain will quit ill get a comparison in times at the local 500ft drag/driveway. It will give a good indication of how much was lost down low.

Recommendations on the 80. FI motors this is a must. Guys with a big CI motor and nitrous......yes, but a head and cam 6.0 or a 5.3......would probably be interested in staying with a built 60 if reliability is not an issue and you just want to go fast!

Summary:
4l60 sucked a big one and blew
Installed 4l80 got aggrivated
changed tune and got a chubby!