I'm having trouble getting the proper calculated gear ratios correct with the 4T80 swap. I changed the individual gear ratios in Tiny Tuner because they aren't accessible in HP Tuners. I think my main problem is the ISS and VSS difference between the 4T65 and 4T80. The 4T65 has a 25 tooth ISS and a 30 tooth VSS. The 4T80 has a 39 tooth ISS and a 31 tooth VSS. The stock 4T65 was a 2.93 FDR so the differential was a 3.29 with 1.121 sprocket ratio. The new 4T80 has a 3.11 differential with a 1:1 sprocket ratio. I'm sure I'm going to be running some messed up numbers because I cannot changed the ISS and VSS numbers in the PCM. Any help would be greatly appreciated.