Line pressure is determined by the TCM according to what gear you are in and by the manual valve bodies in the transmission, however, there is no real feasible way to trick the computer into uping the line pressure because it doesn't have a sensor to state what the line pressure is, only that pressure is there. Otherwise the electronic valves are open\shut type where its either full open or full close and it regulates pressure by preset pulses in the TCM, nothing you can change without going into code. Ummm... what else? The only reason I know this is cause I spent a week at the coffee shop scouring the dealer manual looking for a way to up the line pressure. Needless to say I couldn't find a way. Anywho, I hope this helped.