Two good signs of your pressure being too low is 1) tip "fingering" and 2) leaky gun/spitting.
Sometimes a new tip needs to be broken in a bit, especially the smaller ones; 4-13 and smaller. Are you using the RAC5 tips or the newer RACX guard and tips? I find that Graco's improvements in the RAC X upgrade actually ARE an improvement..
Another problem (for me at least) is that gun you're using. The older Contractor series has a needle set up that can be over-tightened, which can (and has) bent the needle assembly. That causes incorrect seating and that causes leaking and spitting...So far the new Contractor guns have been real good to me, though there are cheaper guns that don't last as long between re-kits but seem to perform ok...
Start with what you have...Make sure your needle is set correctly (factory setup is not always optimal) and experiment with your pressure setting...
Good luck