Go with the 80e to late to worry about gas mileage when you got 6.0 maxx plus blower now GT2-3 cam...Thats a lot of power youll still smoke people left and right.

 

The milage now is not that bad. I get about 12 on the street and 17-18 on the highway....

 

80 for the boost and abuse!!

 

Here are the 60E Gear Ratios:
1st 3.06
2nd 1.63
3rd 1
4th .7

80E Gear Ratios:
1st 2.48
2nd 1.48
3rd 1
4th .75


Kindof gives you an idea of what the overal all ratio should be..
But drivin around in city with the 80E might hurt the MPG because of the higher gearing??

 

Chuck told me that the level 5 should hold up to roughly 550hp. Has anyone ever had a FLT level 5 fail???

 

Most guys change their rear end gear ratios to help with the gearing of the 80e!
Also FLT can install a new gearset in the 80e which would help but its a little pricey

I would recomend the 80e with a higher gear ratio than 3:73s. Higher gear ratio when your cruising in town will help you anyways because you will not need as much throttle to get up to speed, unless you have a large stall. Then again as stated above with the power your making it shouldnt be too bad, i would try it first and if you dont like it then get a higher rear end gear ratio.

 

I run a FLT 4L80E in my Tahoe,it's the only transmission that has ever held up to the torque and weight of my truck.I like the tighter gear spacing of the 4L80E,it felt really great with 4.56 gears but killed rearends on a regular basis so I went back with 3.73 gears.My current setup makes so much torque that I can walk it out then nail the throttle to launch on street tires and still get a respectable 1.9 60' times.Go with the vacuum modulated setup your neck will thank you.

 

I havent seen anyone kill a level 5 but hten again no one has really put them to their limit and had one for a while.

Edit: Turbobeserker had one and I believe he had to limp it to keep it together but hten agian he was making 600+.

 

I havent seen a huge difference in gas milage when I swapped in an 80E...then again if anything its less cause I can beat on the truck more without fear of the trans spilling its guts .

None the less if youre concerned about gas milage loss consider this...lets say there is a few MPG gained with a 60e and you buy one costing ~$3500 that lasts a couple of years before it needs rebuilt. On the other hand you buy a ~$4000 80e that lasts 8yrs before its tired (just guessing on life span here). When you account for down time, cost of removing/installing/rebuilding the units do you come out ahead dollar wise with the few extra MPG going with a 60e or did any savings you saw at the pump get wiped by its relatively short life span.

Just something to consider.....personally Id rather spend a few extra pennies at the pump in exchange for the high probability of not having to walk home every time I mat the gas.

 

Please dont get me wrong guys...i didnt buy a tank and put a blower on it because i thought it was going to get good milage. I was just curious as to how much it would change, thats all.