I highly recommend you start with a ~8lb kit (although I think the centri types quote different pressures than the positive disp pumps). Trust me, you will not be satisfied with power of anything below 8lbs (safe amount of boost to run on the 5.7) and will most surely upgrade right away. The auto is not a downfall but the manuals tend to handle more power. If anything, the manuals are slower but I love slamming my own gears.From your explanation, i may just run 6 lbs for now until my bank account recuperates. I would end up moving up to 8 later. Is having the 8 speed auto transmission a downfall?