You must remove the oil pump first. This entails removing the engine and dropping the 2 oil pans since the oil pump has a lip on it that dips down into the 1st oil pan. I drilled the oil pressure relief hole aprox 20% larger in an attemp to prevent the front main seal from blowing out under high revs. You can see pics of the hole at: www.sidwin.com/supra/oilpump
The hole marked in that picture is the wrong hole. You have to remove the cover to expose the interals of the pump. Then you'll see a larger hole in the pressure relief piston bore. This is the hole that needs to be enlarged.