I dont know for sure what numbers the stock tranny is capable of holding but i know there are some guys out there runnin SCT's on their trucks with tunes capable of 420 hp at the rear wheels on a stock tranny. IM with u on the tranny/converter part does anyone know good brands. I know the dmax guys always run either ATS or Suncoast. Suncoast makes one for the 5r110 torque shift, but does anyone have experience with either brand???