Power Pistol gets you the highest velocity 38 Spl +P loadings with 158 gr LSWC (Speer reloading manual). I use it nearly exclusively in +P loadings with the 158 gr lead bullet. I don't find it flashy at all using lead/cast bullets (it does has a nice boom but to me that is consistent with its performance levels and higher velocities compared to other powders).

Very accurate powder to with low ES/SD.

My favorite 38 Spl +P loading and Speer 158 gr LSWC and CCI 500 primers is 5.6 grs Power Pistol (within Speer's +P data). This load approximates velocity of Rem's 38 Spl +P 158 gr LHP. 5.6 gr load gets approx 970 fps in 6 inch tubes (at least the one I tested).