The turbo LS guys, and naturally aspirated guys running 8's and 9's often pick up .5-1 in ET simply changing from a 4L80e to a TH400 or Powerglide. I know of at least a half dozen Drag Week folks that can attest to this. Weighing highway cruising rpm/speed against competitive ET's. There is a ton of HP tied up in the 4L80e, but it is definitely as strong as a bucket of rocks with very minimal work. The turbo LS guys just install a shift kit (valve body work only) in a stock 4L80e and consistently run dyno'd ~700HP through them and mid-9's.
I'm going to take my chances with a guy that advertises to the turbo LS guys his ability to build reliable 4L60/65e transmissions in 3,600lb cars with 1,200HP. So I'm going to get an "800HP" rated one from him for my hopefully 500-600HP L6.
I agree the 3.06 first gear is steeper than ideal, especially for the rpm drop, but if I plan the system out right, or work with the boost controller (megasquirt) I can have boost in first gear not come on full bore until upper rpm, or for what ever the traction can take, and then by the time it shifts and drops rpm the torque from the boost level is there to pull it back up. Plus, the 60e's overdrive ratio of .70 is better than the 80e's .80.
