I shot IDPA years ago with box stock pistols and did fairly decent. If I flubbed something up, it wasn't because I didn't have enough modifications to my pistol. With 10-8 Performance sights and a trigger job, you've probably done all you really need to do to the gun, other than train with it. Make sure you've got a good belt, holster, and mag pouches. Since IDPA is supposed to be a little more realistic and if you have a CCW, consider that your competetion tools don't differ greatly from your daily carry gear. Fumbling for your gun because you thought it was in a "competetion" rig with which you practice regularly rather than the IWB you're wearing that day would not be a fun situation.
Michael Ross Seeklander recently published a book entitled, "Your Competetion Handgun Training Program." Its around $25 dollars and illustrates a number of daily dryfire and live fire drills in addition to the theory and practice of implementing a realistic individual training program.
Incidently, which 10-8s did you install? I checked their site the other day and saw they now offered a serrated ramp fiber optic front for the M&Ps, and my 45 is ready for a different set of sights.