mborg1,
if u ever wish to go over 10psi then dont flash.
if u plan to stay arround 10psi, and dont want to spend $1000-$1400 on a standalone computer and void your worranty, then flash. it will give u better overall drivability.
u can also try Joe P's FPR (fuel pressure reducer) kit.
it did wonders on my first unflashed MSP. but it only seemed to help 50% of people.
FPR kit is good, but not as good as a flash (if u want to stay arround 10psi).
it all depends on what u plan to do with your car.
ION Performance did 201whp with 10psi, FMIC, and Downpipe.