TexasT is a knowledgeable guy with the 2004R. I personally would step up to a 10 vane pump rotor, supposed to have more consistent pulses and rise or the 7 vane. I went with 13 vane but didn't measure clearance, pressures were low in OD,D and D2, needed a .555 boost valve to get acceptable pressures. The 13 vane is also more prone to breakage, not sure why GM went to the 13 vane, no real advantage to them. Dr Dan(Dan Mascal) on ROP is a great resource, GM tech for years and has built them for big power. You also HAVE to buy the sheet metal pan with the rear, bottom suction filter set up. I have the Hughes deep aluminum pan and 4L60E bottom feed filter. Dan says my set up might be good to 12's with it overfilled. The Sheet Metal pan is all Dan uses on his builds. Make sure you don't get the servo set to tight, no drag or it will burn the band. Mine shifted great but lived a short life. I made sure on this trans that it wasn't too tight. Go for the firmest shift on that Transgo kit, it is on the tame side. Make sure your clearance in the clutch is dead on. These trans are very finicky to get right and live behind big power.