Update! Just passed 35,000 miles since the transgo shift install and the (2) 18,000 GVW double stack coolers running outside of the radiator (they do all the cooling all the time). I have not had a hard shift issue now for over 2.5 years, drive the car routinely at 80-85 mph (Trip to Montreal at those speeds netted 30.5 MPG recently in June 2012-unbelieveable)! Never got that mileage with my other 98 GP GT with the 3.8). The transmission is absolutely perfect with no signs at all that there was ever a problem, 125,000 miles on the 4T65E and the 3.1 with magna flow duals, ubend delete, and 2.5 inch stainless pipes (GMPP exhaust which was just the magnaflow kit for the 3.8 motor). Again, this fix appears durable for the long term if your only problem is a hard shift problem when hot! Pretty unbelieveable that the "experts" seem to some how missed this fix which is MUCH easier than dropping the tranny to change solenoids, and at the end of the day will contribute greatly to the longevity of the 4T65E tranny which gets killed by the tremendous heat retention running the tranny lines through the radiator.
