Originally Posted by 89db
I have a STS M100 with Tightborre 247mm and ARS hopup rubber in my Velocity arms V4A1 and I am at 359 to 362fps with .2g. I highly recommend you to go with a M90. Better be on the safe than on the limit, and 320 fps is a good range to be in at CQB.
+1 Less strain on the internals as well which equals longer life.