[Steve Chryssos]

I have not seen any evidence to support that 4L80E's rob more power than other transmissions. The three common complaints are weight, parasitic loss and overall size. The first two complaints can easily be attributed to stock, ginormus 4L80E torque converters. Once replaced with a true high performance 10" billet converter, the weight comes in line and the parasitic loss myth goes out the window. Hoover saw engine dyno and rear wheel dyno with a net loss of 20%. 575 flywheel and 460 rear wheel. And 4L80E's are simply not that much bigger than a 4L60E. They are just big enough to make room for beefier internals--and that's a good thing.

So, if you keep the 4L80E, just take solace in the fact that it will probably outlast the cars next two paint jobs. The only reason to get rid of it is because the Chrysler NAG1 transmission is a nice piece.