· Cereal Killer
The TH400 became 4L80E around 1991. I had an acquaintance who had access to the Delco source code and was able to alter shift speed and line pressure in the original GM controller. Alter the address maps, burn an EPROM, plug in and chirp the tires. No dirty hands at all.I come from old GM Hydromatic and torque flights were all you had to do was swamped fluids or throw in some tricks shift or put a heavier weight on the governor and bam you got firmer faster shifts.